Treatment results on 695 stage I testicular cancer patients followed with surveillance are described. Seminoma (SGCT) was present in 394 patients and nonseminoma (NSGCT) in 301 patients. Relapses were detected in 155 patients (22%), in 69 patients with SGCT (17%) and 86 with NSGCT (29%). In patients with vascular invasion, relapse was detected in 54% of patients with NSGCT and 38% of patients with SGCT. Time to relapse was median 13 months (range 1 to 84 months) for SGCT and 5 months (range 1 to 171 months) for NSGCT. Forty-nine percent of relapses in SGCT patients were seen within the first year, 87% of the relapses were diagnosed within the first two years, and 98% of the relapses were detected within 5 years. The figures for NSGCT were 80%, 89% and 95%, respectively. Forty-five patients had carcinoma in situ in the contralateral testis, 62% had this together with a seminoma in the other testis. Ten patients died during the follow-up period. None of these deaths were caused by the germ cell tumour or the treatment. The overall survival for patients with stage I disease is 98.6%, and the cause specific survival 100%.