BACKGROUND: There is at present little published information on the current indications for isotretinoin as a treatment of acne vulgaris. OBJECTIVES: To investigate the factors which influence our current prescribing of isotretinoin: acne severity, response to previous therapy, scarring and psychological effect. METHODS: Data on the factors influencing treatment of 200 patients with isotretinoin between January 1993 and May 1994 were examined. RESULTS: 41% of patients were prescribed isotretinoin for partial response to previous therapy, 26% for partial therapy and scarring and 17% for partial response to treatment and psychological disturbance. Only 16 patients received isotretinoin for severe acne. CONCLUSION: Patients who show only partial response to conventional antibiotic therapy should be prescribed isotretinoin in order to minimize scarring and significant psychological disturbance, independently of the severity of the acne.