Objective. By considering the role of adrenergic nervous system in sweat secretion, we postulated that terazosin may be able to improve sweating after taking sertraline, a selective serotonin reuptake inhibitor (SSRI) drug. This study was designed to evaluate the effect of terazosin on sertraline -related sweating. Methods. All patients diagnosed with major depressive disorder based on the DSM-IV criteria who were taking sertraline and suffered from excessive sweating were enrolled in the study and randomly allocated into two groups of receiving terazosin (1 mg) or placebo. Sweating severity was classified using Hyperhidrosis Disease Severity Scale. The patients were evaluated regarding the severity of sweating before beginning of the study and 14 days after taking either terazosin or placebo. Results. Baseline characteristics including age, sex proportion and weight were not significantly different between the two groups (P > 0.05). At the beginning of the study, 33 (48.5%) and 31 (47%) patients in the terazosin and placebo groups, respectively, suffered from the highest grade of sweating. Fourteen days after treatment with terazosin severity of sweating reduced to the lowest grade in 46 (68%) and two (6%) cases in the terazosin and placebo groups, respectively (P < 0.001). Conclusions. Our findings revealed that terazosin may be effective in decreasing sweating severity in patients using sertraline.