The objective of this study was to evaluate the efficacy and tolerability of pregabalin for the treatment of generalized social anxiety disorder (SAD). Patients with generalized SAD, who met the Diagnostic and Statistical Manual of Mental Disorders (fourth edition) criteria (total N=329), were randomly assigned to 11 weeks of double-blind treatment with fixed daily doses of either pregabalin (300, 450, and 600(mg) or placebo. The treatment with pregabalin (600(mg) was associated with a significantly greater mean reduction in the Liebowitz Social Anxiety Scale total score, from baseline to endpoint, compared with placebo (-29.8 vs. -19.7; P= 0.0099), whereas reduction on pregabalin (300(mg, -20.2) and pregabalin (450(mg, -25.5) was not significant Treatment with pregabalin (600(mg) was also associated with a significantly greater improvement than placebo on the fear and avoidance subscales of the Liebowitz Social Anxiety Scale, as well as the majority of other secondary measures. Onset of improvement occurred by week 1 in the pregabalin 600-mg dose group. The most common adverse events on all three doses of pregabalin were somnolence and dizziness. Consistent with a previous study, the results of this study suggest that the 600-mg dose of pregabalin per day may be efficacious in the treatment of SAD.