Venlafaxine extended release (ER) is a dual serotonin-norepinephrine reuptake inhibitor previously shown to be effective in the treatment of major depressive disorder and generalized anxiety disorder. This placebo-controlled, multicenter, randomized, double-blind trial examined the efficacy and safety of venlafaxine ER in outpatients with generalized social anxiety disorder. Two hundred seventy-two outpatients were randomly assigned to receive either a flexible dose of venlafaxine ER (75 to 225 mg/d) or placebo for 12 weeks. Venlafaxine ER was statistically significantly more effective than placebo as demonstrated by the Liebowitz Social Anxiety Scale total scores at weeks 4 to 12. Scores of both the Clinical Global Impression-Severity and Clinical Global Impression-Improvement scales showed that venlafaxine ER was significantly more effective than placebo at weeks 4 to 12. In addition, more venlafaxine ER-treated patients achieved CGI-Improvement scores of 1 or 2 than placebo-treated patients at weeks 4 to 12, demonstrating a greater percentage of responders to venlafaxine ER treatment. Assessment using the fear/anxiety and avoidance subscales of the Liebowitz Social Anxiety Scale and the Social Phobia Inventory Scale also showed venlafaxine ER to be more effective than placebo at weeks 4 to 12 and 6 to 12, respectively. The Sheehan Disability Inventory showed that patients in the venlafaxine ER-treated group had significantly better outcomes in social life at weeks 4 and 12, and in work at week 12. Adverse events were similar to those reported in studies of venlafaxine ER in depression and generalized anxiety disorder. Venlafaxine ER was safe, well tolerated, and efficacious in the short-term treatment of generalized social anxiety disorder.