A family history is one of the strongest risk factors for prostate cancer (PC). We evaluated the detection rate of PC in relatives of 119 German PC families that took part in ongoing linkage analyses. Brothers of patients with sporadic prostate cancer aged < 55 years at onset were included as well. Responses were received from 120/196 (61.2%) individuals of the familial and 67/120 (55.8%) of the sporadic group. Findings (DRE, TRUS, PSA) were more often suspicious for carcinoma in the PC families. Prostate cancer was diagnosed in 6 (5.0%) and 2 (2.99%) participants of the familial and the sporadic group, respectively. These detection rates tended to be higher than that of an age-matched subgroup of an unselected population in other European screening studies. The most important risk factor for the diagnosis of PC was a low average age at onset within the family. These data imply that prostate cancer screening in the high-risk group of men with familial predisposition cannot be assessed by population-based studies and should be evaluated separately.