Two hundred and two patients with gestational trophoblastic tumours (GTT) were treated using single agent etoposide. Patients were divided into low, medium and high risk groups using a prognostic index. Initial chemotherapy commenced with etoposide in 101 patients and 94 were accessible. Partial response (PR), defined by a log fall in serum human chorionic gonadotrophin (hCG) concentration within 1 week, occurred in 63 patients (67%) and was more common among low (5/8; 63%) and medium risk (47/64; 73%) than high risk patients (11/22; 50%) although these differences were not significant (P greater than 0.05). No patient showed a sustained rise in hCG level after etoposide and 91 (97%) showed some decrease. Ninety-one (97%) of these patients remain alive and well with median follow-up of 63 months but 29 (31%) required more intensive combination therapy. Of three deaths, two were due to progressive disease and drug resistance. Among 101 patients who had received previous chemotherapy when etoposide was first administered, response to etoposide was accessible in 39. Of these, PR occurred in 18 (46%) and only one patient progressed after etoposide. With a median follow-up of 35 months, survival in this group is 92% (36/39). All deaths were due to progressive disease and drug resistance. Single agent etoposide is very active in GTT but should be used in combination chemotherapy for patients presenting with adverse prognostic factors.