This report deals with the preliminary results of trials in the DATECA project with stage I, II and III patients with non-seminomatous germ cell tumours. Stage I patients were randomized between infradiaphragmatic irradiation and observation. No significant difference in recurrence rates has been observed as yet. Eighteen of 95 patients had recurrence with a median time to relapse of 3 months. Fifteen patients achieved complete remission after treatment by combination chemotherapy while 3 patients are still undergoing treatment. Stage II patients received 6 series of cis-platinum, bleomycin, and vinblastine. The patients were initially randomized to receive chemotherapy alone versus chemotherapy plus irradiation. Irradiation led to increased toxicity and decreased doses of the antineoplastic drugs. Fifty-one patients were studied. The overall complete remission rate was 89 per cent including 7 patients who achieved complete remission after secondary surgery. Three patients died from testicular tumours and two toxic deaths occurred in this group. Stage III patients were treated with 6 series of cis-platinum, bleomycin, and vinblastine. Fifty patients were studied. The complete remission rate was 72 per cent including 2 patients who achieved complete remission after secondary surgery. Sixteen patients relapsed after achieving complete remission with a median time to relapse of 4 months. Eight of these died, 4 achieved a new complete remission, while 4 patients are still under treatment. Sixty per cent of the patients are at present alive without evidence of disease, while 12 patients died from testicular tumours and 2 from toxic side effects.