Immediately before first hemi-body irradiation, 59 patients with relapsed multiple myeloma were randomised to receive or not to receive subsequent alpha-2b interferon maintenance. 13 patients (22%) [8 of 31 (26%) controls, 5 of 28 (18%) in the interferon arm] received single hemi-body irradiation alone due to progressive disease and/or persistent cytopoenias following the initial procedure. Mean time between upper and lower hemi-body irradiation was 69 days (range 35-294). Of 23 patients randomised to receive interferon and completing double hemi-body irradiation, 15 (65%) achieved peripheral blood counts adequate to allow interferon administration as per study criteria commencing at a mean 116 days (61-241) from time of study entry. The mean period of interferon therapy, starting at a mean 65 days (26-160) post second hemi-body irradiation, is 16.4 months (2-33.5). There was no significant difference in median survival durations (10 months) from time of initial radiotherapy between control and interferon patients.