Between 1983 and 1990, 66 patients were treated with single agent carboplatin for advanced seminoma, and sites of relapse have been analysed with respect to sites involved before chemotherapy. Fourteen relapses were evaluable, and relapse was confined to node groups affected before chemotherapy, or those immediately adjacent, in seven patients. At present it is unclear whether single agent carboplatin should be the initial chemotherapy for seminoma, but if it is employed there may be a role for local adjuvant radiotherapy after carboplatin chemotherapy.