Depressive disorders are very common in clinical practice, with approximately 11.3 of all adults afflicted during any a year. Saffron is the world's most expensive spice and apart from its traditional value as a food additive, recent studies indicate several therapeutic effects for saffron. It is used for depression in Persian traditional medicine. Our objective was to compare the efficacy of hydro-alcoholic extract of Crocus sativus (stigma) with fluoxetine in the treatment of mild to moderate depression in a 6-week double-blind, randomized trial. Forty adult outpatients who met the Diagnostic and Statistical Manual of Mental Disorders, fourth edition for major depression based on the structured clinical interview for DSM-IV and with mild to moderate depression participated in the trial. In this double-blind, single-center trial and randomized trial, patients were randomly assigned to receive capsules of saffron 30 mg/day (BD) (Group 1) and capsule of fluoxetine 20 mg/day (BD) (Group 2) for a 6-week study. Saffron at this dose was found to be effective similar to fluoxetine in the treatment of mild to moderate depression (F = 0.13, d.f. = 1, P = 0.71). There were no significant differences in the two groups in terms of observed side effects. The results of this study indicate the efficacy of Crocus sativus in the treatment of mild to moderate depression. A large-scale trial is justified.