Social phobia is an anxiety disorder characterized by extreme fear and phobic avoidance of social and performance situations and by a relatively poor health-related quality of life. The goal of this study was to compare the efficacy of mirtazapine versus placebo in the treatment of patients with social phobia. In 2004, we conducted a randomized, double-blind, placebo-controlled study of mirtazapine in 66 female subjects from the general population meeting the criteria for social phobia. The subjects were randomly assigned in a 1:1 manner to mirtazapine (n = 33) or placebo (n = 33). The treatment lasted 10 weeks. Seven patients dropped out. Primary outcome measures were self-reported changes on the Social Phobia Inventory, Liebowitz Social Anxiety Scale, and Health Survey (SF-36). In comparison with the placebo group and according to the intent-to-treat principle, significant differences on the Social Phobia Inventory and Liebowitz Social Anxiety Scale scales (all P < 0.001), as well as on most (5 from 8) scales of SF-36 (all P < 0.001), were observed in the mirtazapine-treated subjects. All patients tolerated mirtazapine relatively well. Mirtazapine appears to be an effective agent in the treatment of social phobia in women and in the improvement of their health-related quality of life.