The extensive use of prostate-specific antigen determination has considerably increased the incidence of prostate cancer. Due to earlier diagnosis, localized small cancers are found that in all probability are clinically insignificant. Overdiagnosis leads to overtreatment and to significant adverse effects. Localized prostate cancers of elderly patients having multiple diseases have often merely been monitored without therapy. Active monitoring should now be adventured also for younger men, whose tumor fulfils the criteria of minimal cancer.