Even M0 RCC is associated with tumour progression in approximately 30% of all patients after radical nephrectomy. Nevertheless, no effective adjuvant treatment after radical nephrectomy has been established. In a multicentre phase-III trial we investigated the impact of an adjuvant autologous tumour cell-lysate vaccination on the progression-free survival of patients with M0 RCC after radical nephrectomy. Between January 1997 and August 1998 a total of 558 patients with a renal tumour were enrolled at 55 different centres (study group) in Germany. Prior to radical nephrectomy all patients were centrally randomized (Quintiles Germany) to either receive an adjuvant autologous tumour cell-lysate vaccine (6 applications at 4-week intervals after radical nephrectomy) or to receive no adjuvant treatment (control group) after radical nephrectomy. All patients were evaluated following standardized diagnostic investigations at 6-month intervals. Following the inclusion criteria (RCC stages pT2-3bpN0-3M0, TNM-classification, UICC 1993), 365 patients were evaluable for the 3-year progression-free survival analysis. There were 240 patients with stage pT2pN0M0 (104 in the vaccine group and 136 patients in the control group) and 89 patients with stage pT3pN0M0 (46 in the vaccine group and 43 patients in the control group). The remaining 36 patients had positive lymph nodes. The trial was performed according to ICH-GCP guidelines. The 3-year progression-free survival rate for all tumour stages was 84.7% in the vaccine group and 80.9% in the control group. Patients with RCC stage pT3pN0-3M0 in the vaccine group demonstrated an advantage (74.4% in the vaccine group vs 65.9% in the control group). For RCC stage pT2pN0-3M0 the 3-year progression-free survival rate in the vaccine group was 89.7% compared to 85.7% in the control group. Follow-up of all patients enrolled in this trial is ongoing. This is the first randomized trial indicating a benefit from an adjuvant vaccination in patients with M0 RCC after radical nephrectomy. The advantage in terms of progression-free survival was more pronounced in patients with T3-tumours. However, it must be emphasized that the results of the final study report (2003) must be awaited before definite recommendations can be made.