BACKGROUND: Information on risk of benign prostate hypertrophy (BPH) in HIV-infected men is sparse. We aimed to estimate the incidence of being diagnosed with BPH among HIV-infected men compared with an age and sex-matched comparison cohort from the background population. To exclude that family-associated risk factors influence risk of BPH diagnoses in families of HIV-infected individuals, we estimated risk of BPH in fathers of HIV-infected men and fathers of the comparison cohort. METHODS: In a nationwide, population-based, matched cohort study, we calculated incidence rates and used Poisson regression models to calculate incidence rate ratios (IRRs) of being diagnosed with BPH, defined as the earliest of date of the second redeemed prescription of a drug used to treat BPH, the first registration of a BPH diagnosis in the Danish National Hospital Registry (DNHR) or the first registration of a surgical procedure for BPH in DNHR. RESULTS: We identified 4633 HIV-infected men, 46 330 comparison cohort individuals, 1585 fathers of HIV-infected men and 20 449 fathers of the comparison cohort. Incidence rate of being diagnosed with BPH was 37.0 [95% confidence interval (95% CI) 31.5-43.1] per 10 000 person-years of follow-up among HIV-infected men and was not increased compared with the comparison cohort (IRR 1.04, 95% CI 0.88-1.22). Risk was not increased for fathers of HIV-infected men vs. fathers of the comparison cohort (IRR 0.99, 95% CI 0.87-1.12). Stratified analyses did not change the above results markedly. CONCLUSION: HIV-infected individuals do not have an increased risk of being diagnosed with BPH.