Background: Road traffic accidents are considered a major threat to public health worldwide and are usually referred as “hidden epidemic”. In developing and middle-income countries, however, worries are more severe. For example, a national study in Iran found that traffic accidents ranked first in the number of years of life lost due to premature death in Iran. Various studies have divided the factors affecting the occurrence of traffic accidents into three categories: human, vehicle, and environmental factors. The human factor has a decisive role in the occurrence of accidents. In a way that based on studies, this role in traffic accidents could be 70 to 90%. It is clear that study in this area, like other research, requires data collection. Since archival information about driverschr('39') behavior is often incomplete and difficult to obtain, researchers often have to evaluate driving behaviors using self-report tools. One of the foremost common self-reporting instruments used in research focused on driver behavior is the Manchester Driving Behavior Questionnaire (MDBQ). The only complete Persian version of MDBQ has been published by Oreyzi et al. (2010). The authors of the present study had initially intended to use a Persian MDBQ questionnaire to conduct a field study. But while comparing this questionnaire with the original one (in English), they found several shortcomings in the Persian version. For example, it can be mentioned the lack of attention to the difference between regular driving of the road in the UK (on the left side) and in Iran (on the right side). Since the accuracy of data collection tools is vital in research, the authors intended to revise the Persian version of this widely used questionnaire. The purpose of this study was to re-evaluate the psychometric properties of MDBQ. Methods: The original MDBQ version developed by Reason (1990) with 50 items responding in a five-point Likert scale (never = 1 to always = 5). The items are divided into four categories according to the type of behavior including slip, deliberate violation, mistake, and unintentional violation. To evaluate the psychometric properties of the Persian version of MDBQ, the linguistic, face, and construct validity were check, as well as, instrument reliability. For assessing the linguistic validity of the questionnaire, the original version of the DBQ questionnaire was translated by English-speaking experts, one of whom had more than ten years of driving experience in European countries. In this way, it was possible to implement traffic signs and regulations in the country of origin and Iran (localization of items). This was followed by other linguistic validity steps. To investigate the qualitative face validity of the questionnaire, the questionnaire was given to 15 drivers to express their views on each of the questionnaire items in terms of difficulty, appropriateness, ambiguity, relevance, and ambiguity of the instrument items. To study the quantitative face validity of the items (impact factor), the questionnaire was given to 14 members of the target group (drivers) and asked to rate the importance of each item in the questionnaire in a five-point Likert scale (from not important at all = 1 to very important = 5). The criterion for accepting each item is the score of the impact factor, which should not be less than 1.5. Content validity was studied using the content validity ratio (CVR) and content validity index (CVI). For this purpose, a questionnaire was provided to 10 members of the expert panel (expert on safety and occupational health and health education) who were fully acquainted with the content validity assessment. After making the necessary changes based on the expert panel opinions, the mentioned indicators were calculated. To evaluate the CVR (necessity of each item), the group of experts was asked to classify each item according to the three-point Likert scale (essential = 1, useful but not necessary = 2 and not necessary = 3). Then the content validity ratio was calculated. The CVR acceptance criterion based on the number of experts (n = 10) was 0.62 and the minimum CVI acceptance was 0.79. In this study, 500 participants (drivers) took part in the phase of the construct validity evaluation. To access these people, parking lots, commercial complexes, parks, etc. were referred to. All drivers with a driving license could potentially be among the participants, except for illiterate drivers and drivers with less than three years of driving experience. Informed consent was obtained from all participants prior to submitting the questionnaire. Statistical tests were performed using SPSS 16 at the significant level of 0.05. In this study, Bartlett’s Test (BT) was applied to ensure that there were sufficient correlations between the statements in the questionnaire to be able to integrate them and cover the factors. The rotated factor matrix was used to interpret the functional structures of the Manchester Driving Behavior Questionnaire. To determine the number of MDBQ questionnaire factors the Scree Plot and Eigenvalue methods were used in this study. Cronbachchr('39')s alpha coefficient was used to evaluate the internal consistency in this study. For this purpose, the alpha value above 0.7 was considered acceptable. Results: The linguistic validity, as well as, comparing each item of the available Persian version of MDBQ (2010) with the original English version revealed that besides, shortcomings in translation, there were technical and cultural in some items of previous Persian version MDBQ (2010). The authors classified all shortcomings into three groups as follows: Criticism 1: Differences in the regulation or signs of driving in Iran and the United Kingdom (such as driving on the left side of the road; or the lack of a specific shape of the line in Iran). Criticism 2: Translating the items into Persian, including incorrect translation or deletion of some words. Criticism 3: Editing items (such as inappropriate verb tenses, prepositions, pronouns, etc.). At first glance, this critique may seem to be a matter of taste. However, it should be noted that an easy understanding of the items can have a serious effect on the correctness of the participantschr('39') responses. The amendments, based on differences in traffic rules or signs in the two countries, included 8 items (16 percent). While incorrect translation, 34 items (68%) and non-fluent items accounted for 18 items (36%). It should be noted that for some items, only one modification was sufficient, but some required two or three modification s. Of the 43 items changed, 28 items (56 percent) required one, 13 items (26 percent) required two, and two items (4 percent) required three modification/s. It is obvious that Criticism 2 (editing the items) has given itself the most abundance. One of the things that came back to this critique was the use of the words vehicle, machine, and automobile at random to translate the words vehicle and car. In the suggested version, the appropriate equivalent fixed words for vehicle and car have always been used in translation of the items. Also in the suggested version, the authors intentionally changed the translation of some of the items. Because, in the English version, there were cases that were not compatible with the conditions of Iran, such as: In item 8, the multi-level car park is mentioned that in some cities of Iran this type of parking does not exist yet. For this reason, the word "multi-level" was removed from the item. In items 26, a restaurant and a pub are mentioned, which are consumed in accordance with the western culture of alcoholic beverages in these places. Due to the lack of such places in Iran, this phrase has been omitted. Instead, given the importance of drug and sleeping pills use, this has been added to the item. In item 27, the original questionnaire does not provide an example for this item, but the authors concluded that in order to better understand the respondents to this item, it is better to provide examples. In item 28 refers to pelican crossing, which does not currently exist in Iran. In item 29, the double-yellow line is mentioned, which is not common in Iran at the moment. As a result, the authors used the phrase "no parking area" instead, which is the closest concept to the double-yellow line in terms of content. In face validity, two items were corrected according to the participants. The CVI values of all items were above 0.79 and the CVR values for all items were higher than those suggested by Lawshe. Thus, all items were retained. Exploratory factor analysis (EFA) showed that the four extracted factors account for 51.6% of total item variance. All 50 items had a factor load greater than 0.4. Therefore, none of the items in the questionnaire were omitted. As a consequence, the MDBQ was retained with the same four factors and 50 items of the original questionnaire. Conclusion: The new Persian version of MDBQ was able to correct the defects and weaknesses of the previous version. The finding showed that despite minor cultural differences, the MDBQ had satisfactory reproducibility, internal consistency, and validity consistency between the items in the new version of the questionnaire is desirable and the items in each of the four domains measure the characteristic well. Our result showed that application of this new Persian version in the target groups was acceptable, easy, and comprehensible and attracted cooperation and motivation to respond.