No controlled trial of treatment of generalised social phobia has been conducted in general practice. To examine the efficacy of sertraline or exposure therapy, administered alone or in combination in this setting. Study was of a randomised, double-blind design. Patients (n = 387) received sertraline 50-150 mg or placebo for 24 weeks. Patients were additionally randomised to exposure therapy or general medical care. Sertraline-treated patients were significantly more improved than non-sertraline-treated patients (chi(2)=12.53, P<0.001; odds ratio=0.534; 95% Cl 0.347-0.835). No significant difference was observed between exposure- and non-exposure-treated patients (chi(2)=2.18, P=0.140; odds ratio=0.732; 95% Cl 0.475-1.134). In the pairwise comparisons, combined sertraline and exposure (chi(2)=12.32; P<0.001) and sertraline (chi(2)=10.13; P=0.002) were significantly superior to placebo. Sertraline is an effective treatment for generalised social phobia. Combined treatment with sertraline and exposure therapy, conducted by the general practitioner, may enhance the treatment efficacy in primary care.