Thirty male patients (28 homosexual or bisexual) with biopsy proven chronic active hepatitis B were randomised to receive lymphoblastoid interferon (Wellferon) or no treatment. All patients were HBeAg-positive and had continuing viral replication. Interferon was given as a single daily i.m. injection for 28 days at a starting dose of 2.5 megaunits/m2 increasing to a maximum of 7.5 megaunits/m2/day. Transient side-effects occurred in all patients. Hepatitis B viral replication was suppressed during interferon treatment in all patients but the effect was limited to the period of therapy. After 1 year there was no appreciable difference in viral markers between the two groups of patients and this treatment schedule appears less effective than the thrice weekly, 3-month regimes reported from other centres.