To assess the value of autolymphocyte therapy (ALT) in the treatment of metastatic renal-cell carcinoma, 90 patients were randomised to receive every month for six months oral cimetidine plus an infusion of autologous peripheral blood lymphocytes activated in vitro by a previously generated autologous lymphokine mixture, or cimetidine alone. The median follow-up was 15 months. Survival time for the autolymphocyte group was approximately 2.5 times that for the cimetidine group (p = 0.008). Patients who had greater than 500 pg interleukin-1 (IL-1) per ml autologous lymphokine mixture had a six-fold survival advantage over those with less than 500 pg/ml (p less than 0.00005). Men treated with ALT had a four-fold survival advantage (p = 0.001) over men who received cimetidine only. Infusion of the cultured autolymphocytes was accompanied by mild, self-limited fever in 11 of the 45 ALT patients, and by only one instance in which fever was accompanied by tachypnoea and hypotension.