The purpose of this study was to examine the relationship between androgenetic alopecia (AA) and prostate cancer with particular emphasis on early age at diagnosis and higher grade tumors. We conducted an age-stratified, population-based case-control study in Australia of men who were diagnosed before 70 years of age during 1994-1997 with histopathology-confirmed adenocarcinoma of the prostate, excluding well-differentiated tumors. Controls were selected from the electoral rolls, and the frequency was matched on age. After excluding subjects with missing values, the analysis was based on 1446 cases and 1390 controls of whom direct observations were made of their pattern of AA during face-to-face interviews. Our data suggest an association between prostate cancer and vertex baldness; compared with men who had no balding, the adjusted odds ratio (OR) was 1.54 (1.19-2.00). No associations were found between prostate cancer and frontal baldness or when frontal baldness was present concurrently with vertex baldness. The ORs were 0.98 (0.79-1.23) and 1.14 (0.90-1.45), respectively. The highest ORs were for high-grade disease in men 60-69 years of age: 1.80 (1.02-3.16) for frontal baldness; 2.91 (1.59-5.32) for vertex baldness; and 1.95 (1.10-3.45) for frontal and vertex baldness. This association between the pattern of AA and prostate cancer points to shared androgen pathways that are worthy of additional investigation.