Background: Walking ability is an important prerequisite for activity, social participation and independent living. While in most healthy adults, this ability can be assumed as given, limitations in walking ability occur with increasing age. Furthermore, slow walking speed is linked to several chronic conditions and overall morbidity. Measurements of gait parameters can be used as a proxy to detect functional decline and onset of chronic conditions. Up to now, gait characteristics used for this purpose are measured in standardized laboratory settings. There is some evidence, however, that long-term measurements of gait parameters in the living environment have some advantages over short-term laboratory measurements., Methods: We evaluated cross-sectional data from an accelerometric sensor worn in a subgroup of 554 participants of the Berlin Aging Study II (BASE-II). Data from the two BASE-II age groups (age between 22-36 years and 60-79 years) were used for the current analysis of accelerometric data for a minimum of two days and a maximum of ten days were available. Real world walking speed, number of steps, maximum coherent distance and total distance were derived as average data per day. Linear regression analyses were performed on the different gait parameters in order to identify significant determinants. Additionally, Mann-Whitney-U-tests were performed to detect sex-specific differences., Results: Age showed to be significantly associated with real world walking speed and with the total distance covered per day, while BMI contributed negatively to the number of walking steps, maximum coherent distance and total distance walked. Additionally, sex was associated with walking steps. However, R2-values for all models were low. Overall, women had significantly more walking steps and a larger coherent distance per day when compared to men. When separated by age group, this difference was significant only in the older participants. Additionally, walking speed was significantly higher in women compared to men in the subgroup of older people., Conclusions: Age- and sex-specific differences have to be considered when objective gait parameters are measured, e.g. in the context of clinical risk assessment. For this purpose normative data, differentiating for age and sex would have to be established to allow reliable classification of long-term measurements of gait., Competing Interests: Martin Daumer, Scientific Director of the Sylvia Lawry Centre for Multiple Sclerosis Research e.V. (SLC) and one of the two Managing Directors of Trium Analysis Online GmbH, serves on the Editorial Board of MedNous and holds Patent 10 2007 044 705.3-35, German patent and trademark office 307 19 449.3/09. The Sylvia Lawry Centre received honoraria for interviews of Dr. Daumer with Propagate Pharma Limited and Deerfield Research LLC; is Medical Advisor of the German Multiple Sclerosis Society; received honoraria for consultancy, statistical analysis and use of actibelt technology from the following entities: Bayer Schering, Biopartners, Biogen Idec, Biogenerix, Böhringer-Ingelheim, EISAI Limited, Heron Evidence Development Ltd, Hoffmann-La Roche, Johnson & Johnson Pharmaceutical Research & Development LLC, Sanofi-Aventis U.S. INC., Novartis Pharma GmbH, University of Oxford, Imperial College London, University of Southampton, Charité Berlin, University of Vienna, Greencoat Ltd, University Medical Center Hamburg-Eppendorf. Timur Nuritdinow and Christian Lederer are employees of the Sylvia Lawry Centre for Multiple Sclerosis Research. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials, as detailed online in the guide for authors. Dr. Steinhagen-Thiessen reports grants and personal fees from Sanofi, personal fees from MSD, Fresenius, personal fees from Amgen and Chiesi, outside the submitted work. Dr. Demuth reports grants from Sanofi, personal fees from uniQure biopharma B.V., outside the submitted work. All other authors declare no conflict of interests. T.M., C.L. and M.D. are associates of Trium Analysis Online GmbH, (Munich, Germany) as the developing company of the actibelt tri-axial accelerometer. These authors were involved in the conceptualization of the study, data preparation, statistical analysis and writing of the manuscript. However, Trium had no role in financing the BASE II-study or the preparation of the manuscript presented here. As authors, they were involved in the writing, reviewing and approval of this manuscript for publication. The involvement of these authors does not alter our adherence to PLOS ONE policies on internationally-accepted standards for research practice and reporting, including data management, figure preparation, reproducibility, and reporting guidelines as well as sharing data and materials.