250 patients with clinical stage 1 non-seminomatous germ cell tumours of the testis (NSGCT 1) were included into a prospective multicentre protocol during 1990-1994 and treated according to three risk strata: patients without tumour cell invasion of vascular structures in the testis (VASC-) and elevated serum AFP levels (AFP+) at orchiectomy were considered low risk (LR) and only observed closely. VASC- and AFP- or VASC+ and AFP+ patients were presumed intermediate risk (IR) and pathologically staged (PS) by retroperitoneal lymph node dissection (RPLND). VASC+ and AFP-patients were regarded as high risk (HR) and received adjuvant chemotherapy (PEB x 3). At a median observation time of 40 (7-68) months, all patients were alive and without evidence of active germ cell cancer. The actuarial relapse rate in the 106 LR patients was 22%, and 70% (14/20) had elevated serum tumour markers at relapse. One of 32 (3%) HR patients relapsed with a resectable retroperitoneal mature teratoma despite adjuvant chemotherapy. Only 14% of the 99 IR patients who underwent RPLND had PS2 disease, and the actuarial relapse rate in 85 PS1 patients was 18%. This multicentre study demonstrated that excellent therapeutic outcome is possible when 18 comparatively small urological and oncological centres follow a strict and formal cancer care programme. The useful prognostic effect of VASC was once again verified. Pathological staging by RPLND in NSGCT1 is, in our opinion, not necessary, with presumed low-risk patients offered surveillance and high-risk patients offered adjuvant chemotherapy.