Background: Minoxidil is currently an approved treatment for androgenetic alopecia. Topical tretinoin can enhance skin absorption of minoxidil. Objective: This study has been done in order to determine the efficacy and safety of the solution of 0.5% minoxidil+0.05% tretinoin compared to 2% minoxidil in androgenetic alopecia in men. Patients and Methods: In a randomized, double-blind, parallel-group, controlled study, 117 male patients with androgenetic alopecia, 18-40 years old, Hamilton grades of 2-5 and duration of alopecia less than 10 years were evaluated. These patients were divided in two groups randomly, one group received a solution containing 0.5% minoxidil and 0.05% tretinoin and another group received 2% minoxidil for at least 4 months. The patients used 1ml of the solution twice daily. 2 and 4 months after treatment, the patients were evaluated for efficacy (Patients, idea about improvement of hair loss, hair regrowth and wash test) and safety (Erythema, scaling and pruritus). The quantitative data were analyzed by ANOVA and the qualitative data were analyzed by qui-squared test. Results: There were no significant differences between two groups regarding the age, duration and grade of hair loss. After 4 months of treatment, the percentage of patients reporting improvement in hair loss and hair regrowth were 81.6% and 56% in minoxidil 2% group and 65.4% and 59.6% in minoxidil+tretinoin group, respectively (P>0.05 for all). At the same time, the numbers of hairs in wash test were 156 in minoxidil 2% group and 149 in minoxidil+tretinoin group (P>0.05). Conclusion: There was no significant difference in efficacy and safety of 4 months treatment with the solution of 0.5% minoxidil and 0.05% tretinoin compared to the solution of 2% minoxidil in the treatment of androgenetic alopecia in men.