Purpose: We aimed to evaluate the associations between androgenetic alopecia at a young age and subsequent development of aggressive prostate cancer (PC). Methods: Using a case–control design with self-administered questionnaire, we evaluated the association between aggressive PC and very early-onset balding at age 20, and early-onset balding at age 40 years in 1,941 men. Cases were men with high-grade and/or advanced stage cancer and controls were clinic based men who had undergone biopsy and were found to be histologically cancer negative. Additionally, for cases we assessed whether early-onset balding was associated with earlier onset of disease. Results: Men with very early-onset balding at age 20 years were at increased risk for subsequent aggressive PC [odds ratio (OR) 1.51, 95% confidence interval (CI) 1.07–2.12] after adjustment for age at baseline, family history of PC, smoking status, alcohol intake, body shape, timing of growth spurt and ejaculatory frequency. Additionally, these men were diagnosed with PC approximately 16 months earlier than cases without the exposure. The effect was present particularly for men with advanced stage pT3+ disease (OR 1.68, 95% CI 1.14–2.47) while men with organ-confined high-grade (8–10) PC did not exhibit the same relationship. No significant associations were observed for men who were balding at age 40 years, given no balding at age 20. Conclusion: Men with androgenetic alopecia at age 20 years are at increased risk of advanced stage PC. This small subset of men are potentially candidates for earlier screening and urological follow-up.