BACKGROUND:Proteinuria has been associated with bone loss and fractures in general population, but data in HIV-infected population are lacking. SETTING:Prospective, multicenter cohort study of men with or at risk of HIV infection. METHODS:Between 2006 and 2015, urine protein measurements and bone fracture histories were ascertained semiannually in 947 HIV-infected (HIV+) and 969 HIV-uninfected (HIV-) men aged 40 years or older. Proteinuria was defined as protein-to-creatinine ratio ≥200 mg/g at ≥2 consecutive visits. Outcome measures (1) all fractures (excluding fractures of skull, face, and digits) and (2) fragility fractures (fractures of vertebral column, femur, wrist, and humerus). Multivariable Cox proportional hazards models assessed the association between proteinuria and fracture after adjusting for additional risk factors. RESULTS:The overall period prevalence of proteinuria was higher among HIV+ than HIV- (29% vs 6%, P < 0.001). Men with proteinuria had a significantly higher risk of fragility fracture compared with men without proteinuria [adjusted hazard ratio (aHR) = 2.29 (1.12-4.66)] and did not differ by HIV serostatus (p-interaction = 0.83). The risk of all fractures was not statistically different between men with or without proteinuria [aHR = 1.31 (0.84-2.05)]. Among HIV+ men, the association between confirmed proteinuria and fragility fracture was attenuated [aHR = 2.12 (0.95-4.73)] after additional adjustment for CD4 T-cell count/mm, history of AIDS, the presence of detectable plasma HIV-1 RNA, and cumulative exposure to tenofovir disoproxil fumarate. CONCLUSIONS:Proteinuria was more common in HIV+ than in HIV- men and was a strong independent risk factor for fragility fracture regardless of HIV serostatus. Proteinuria should prompt consideration of a thorough evaluation for bone disease among HIV+ persons.