OBJECTIVE: The effectiveness of pindolol as an adjunctive treatment to boost response to selective serotonin reuptake inhibitors (SSRIs) in patients with generalized social phobia was tested. METHOD: A double-blind, placebo-controlled, crossover design was used to compare addition of 5 mg of pindolol t.i.d. or placebo for 4 weeks to a steady paroxetine dose. Subjects were 14 patients with generalized social phobia who were less than "very much improved" on the Clinical Global Impression scale after at least 10 weeks of treatment with a maximally tolerated dose of paroxetine. Changes on the Liebowitz Social Anxiety Scale and the Social Phobia Inventory scores were compared across the two crossover periods. RESULTS: Pindolol was not significantly superior to placebo for augmenting the effects of paroxetine on social anxiety symptoms. None of the 14 subjects was deemed a responder to the pindolol arm of the crossover. CONCLUSIONS: Pindolol was no more effective than placebo in augmenting the effects of SSRI treatment for generalized social phobia.