Objectives : The current study aimed to provide a systematic review of studies conducted between 1998 and 2008 on the primary healthcare program (PHC) in Iran. Method: Electronic and manual search of a number of internal and external databases and resources (including Pubmed, IranDoc, SID, IranPsych, Embase, PsycINFO, and Iranmedex) were conducted as well as interviews with professionals in the sector. In total, of the 156 research abstracts that were obtained, 26 reports and research programs relating to the subject of integration of mental health care in PHC in Iran were selected. Results: Studies suggest that, in its 20-year gradual expansion, the integrated program has covered 54.6% of the country’s population (specifically 95.2% of rural and 36.6% of urban population). Moreover, the total number of case findings by health workers increased from 4.3 to 14.7 persons in every thousand of the population . Nine assessments conducted to examine knowledge and attitudes of health workers and individuals in the community towards mental health indicated positive improvements in these factors. Conclusion: The integration of mental health care in PHC program has been successful in smaller cities and rural areas, but it has not been responsive to populations of large metropolitan cities in Iran. Therefore, there is an urgent need to revise this program .