Background & Aims: Introduction: Autism Spectrum Disorder (ASD) is a neurological developmental disorder characterized by impaired social interactions, stereotypic movements and repetitive and limited behaviors and interests. Given the increasing statistics of autism in children in the world and in Iran, the extent of problems and burdens that this disorder creates for the child, family and society, it is a necessity to identify the causes and factors related to ASD. Moreover, data on this disorder are limited nationally and geographical differences are rarely assessed. To conduct great research on autism spectrum disorders requires a large number of samples to identify the epidemiological trend of the disorder. Registrations are one of the efficient methods that can provide this data in a long time and on a large scale. The purpose of this study is to describe the steps of designing and launching an autism registration system in Tehran, which can be a prelude to creating a system at the national level. Methods: In this study, the aim was to present a protocol to design and launch a registry for patients with autism spectrum disorders in Tehran for clinical and research purposes. The entered population in this system includes individuals (including children over 6 months and adults) with previous diagnosis or new diagnosis referred to the certain centers (Child Psychiatric Clinic of Tehran Psychiatric Institute, Ali Asghar Children's Hospital, Razi Hospital and Roozbeh Hospital) and also, physicians' offices who are members of the program's strategic committee. Patients are admitted to the program if the diagnosis of ASD is confirmed by a pediatrician, child neurologist, psychiatrist, neurologist, psychiatrist, neurologist, child psychologist according to the DSM-5 diagnostic criteria. Then personal and demographics information and clinical and laboratory findings will be recorded by data entry experts in the system. Patients will be followed up by telephone or through coming back of the patients to the certain centers. Data analysis is done in accordance with the objectives of the registration program and is performed based on conventional statistical methods. Also, an annual report of the profiles of registered patients is sent to the beneficiaries of the program at the end of each year, including the Vice Chancellor for Research of the participating universities, the Ministry of Health, and related associations and groups. Initially, stakeholders in the field of autism spectrum disorders from different and related specialties were identified from partner universities of medical sciences in Tehran (Iran, Tehran, Welfare Sciences) and various centers accepting autism spectrum patients and the Strategic Committee for Autism Registration as a subset of the Vice Chancellor for Research was established in 1398 in Iran University of Medical Sciences. The Strategic Committee is responsible for developing guidelines and executive protocols consisting of experts in the fields of general psychology, child psychology, social medicine, epidemiology, information technology, health informatics and health information management, as well as the executive committee and executive groups for follow-up and conducting decisions of Strategic Committee was considered. Data Management and Information Technology (IT) Department was Responsible for Software Design; Data collection and quality control group was responsible for data collection, quality control, feedback and data correction; The epidemiology and data analysis team was also responsible for designing and conducting the data analysis program. The population entered in this system includes people (including children over 6 months and adults) with previous diagnosis or new diagnosis of the referral centers. A child is considered to have diagnostic criteria for autism spectrum disorders according to the DSM 5 Diagnostic Guide if he or she has serious impairments in communication and social interactions as well as a limited and repetitive pattern of behavior, interests, and activities. Patients enrolled in the program have been diagnosed with ASD by a pediatrician, child psychiatrist, pediatric neurologist, psychiatrist, or neurologist. Child Psychiatric Clinic of Tehran Psychiatric Institute, Ali Asghar Children's Hospital, Razi Hospital and Roozbeh Hospital and also physicians' offices who are members of the program's strategic committee are covered now. Based on the objectives of the Strategic Committee and literature review for the design of registration systems, the following data collection was considered: - Personal and socio-demographic characteristics (such as name, age, gender, ethnicity, parents' relatives, place of birth and residence, birth rank, education) - Clinical information (such as history of developmental delay, name of the disorder, presence of seizures, presence of mental retardation and other psychiatric diagnoses, personal and family history of the disorder) - Laboratory and imaging finding Then personal and demographics information and clinical and laboratory findings will be recorded by data entry experts in the system. Patients will be followed up by telephone or through coming back of the patients to the certain centers. Data analysis is done in accordance with the objectives of the registration program and is performed based on conventional statistical methods. Also, an annual report of the profiles of registered patients is sent to the beneficiaries of the program at the end of each year, including the Vice Chancellor for Research of the participating universities, the Ministry of Health, and related associations and groups. In order to validate and evaluate the feasibility and ease of implementation of the data collection form, this form was piloted in several centers and then based on the results of experimental implementation, the questions were reviewed and finalized. After compiling the final version of the data collection form, the software registry system was designed for the web. In order to maintain data security, a separate access and a specific access level for each user is determined and hosted on the servers of Iran University of Medical Sciences .Data analysis is done in accordance with the objectives of the registry and is performed based on the required statistical methods. Also, an annual report on the profile of registered patients of the registry is sent to the beneficiaries of the program at the end of each year, including the Vice Chancellor for Research of the participating universities, the Ministry of Health and related associations and groups. In 2014, the Deputy Minister of Research at the Ministry of Health and Medical Education (MOHME) of Iran decided to establish registration systems for various diseases and health consequences (4). In this regard, the launch of a clinical-research registry in autism in Tehran was considered .Setting up an autism spectrum disorder information registry in Tehran as a preliminary study for its establishment at the national level can help to integrate research activities and create a research network and prevent incoherence, rework and waste of time and energy in related research activities in the country. In addition to the direct use of data for research activities, such systems can also be used to identify patients eligible for clinical trials. In addition, it is possible to study the natural course of this disorder, track individuals and help increase the country's indigenous knowledge based on local and regional information. In addition, launching a program to record the autism spectrum disorders will help policymakers and health planners in the country to decide and plan for it. In addition, is not possible for policy makers to plan in an integrated, comprehensive, accurate and up-todate way without having access to such online information systems. In the long run, this study aims to record all ASD information across the country in this system to eliminate the huge challenges of patients, physicians and health decision makers and also Smoothing the way for research further. Conclusion: Establishing registry systems, especially chronic diseases seems to be a need for work so that health policy makers can make the right policies and plans to improve the level of health. One of the most important features of registries is the enrolling of patients in the time period and the possibility of increasing the collection of patients in the country. Due to the relatively high prevalence large number of causes and increasing high financial burden of autism spectrum disorders that it imposes on society, it is a suitable c case to evaluate prevalence, environmental and genetic factors through recording all clinical and epidemiological information [ABSTRACT FROM AUTHOR]