This multicentre double-blind trial in general practice compared the efficacy and tolerability of the sustained-release formulation of clomipramine (Anafranil SR) with its conventional formulation (Anafranil) in the treatment of phobias. Patients were allocated at random to receive clomipramine 75 mg once daily as either the sustained-release or conventional formulation for 11 weeks following a 1-week dosage build-up period. Analysis of results from forty-six patients showed that the sustained release formulation of clomipramine 75 mg was as effective as the conventional formulation of clomipramine 75 mg in improving symptoms of phobia as assessed by a phobia inventory and global evaluation. Unwanted effects attributable to therapy were similar in both treatment groups but there were fewer withdrawals due to unwanted effects of the sustained release formulation of clomipramine 75 mg. It was concluded that the sustained-release formulation of clomipramine does offer advantages for patients requiring 75 mg clomipramine daily.