A group of 74 patients among 1,663 patients with biopsy-proven prostate cancer of various stages who, contrary to the usual practice, received no treatment were followed at the outpatient clinic of the Inselspital university hospital in Berne, Switzerland. The aim of this study was the evaluation of the number of patients eventually succumbing to cancer of the prostate, the survival figures for these patients, and the prognostic value of minimal clinical staging. Thirteen patients had hormonal treatment at a later stage, but 61 of 1,663 patients (3.7%) were never treated for prostate cancer. Overall survival for all 61 patients was 50% at 5 years and 24% at 10 years. Overall disease-specific survival was 75% at 10 years. In the group with organ-confined disease (T0-2) actuarial 5- and 10-year survival rates were 67 and 34%, respectively, whereas in the group with extraprostatic disease (T3-4) the respective survival rates were 11 and 0%. Disease-specific 5- and 10-year actuarial survival was 89% in the T0-2 group and 51 and 0% in the T3-4 group. The cause of death in 30 patients was reported as disease-related in 8 patients (26.6%), unrelated to prostate cancer in 18 patients (60%) and unknown in 4 patients (13.3%). Despite the absence of treatment for a mostly clinically overt prostate cancer the majority of patients apparently did well and eventually died from other causes.