Background and Purpose: Self-medication is an important concern in every part of the world. The aim of this study was to estimate the prevalence and to investigate the associate factors of self-medication among adults in Gorgan, north of Iran. 
Materials and Methods: This descriptive cross-sectional study was carried out among adults aged 12 years and above who were residents in Gorgan city. The participants were selected using the multi-stage cluster sampling method. SPSS Software and Pearson's chi-squared test were used for data analysis.
Results: A total of 592 households with 2050 respondents were visited. The prevalence of self-medication was 67.9%. A larger number of females were self-medicating (71.3%) than males (63.5%). The majority of the respondents self-medicated because of the previous use experience (59.3%). The main indication for self-medication use was headache (60.8%).  Analgesics were the most commonly self-medicated by the respondents (83.9%). Also, 88.6% of the respondents prepared their drug from drugstores. Furthermore, there were significant differences between self-medication and demographics characteristics including gender, age group, marital status, occupation, education level and income (p<0.05).
Conclusion: The prevalence of self-medication especially with analgesics is relatively high among adult city-dwellers in Gorgan. So, preventive measures, such as strengthening of the communities awareness on the side effects of self-medication practice and regulation of pharmacies are very important mechanisms to decrease the practice.