The importance of pubertal timing for adult BMD in males was studied through association of pubertal timing with young adult bone phenotype. Pubertal timing was found to predict both cortical and trabecular volumetric BMD and previous fractures in young adult men. Thus, late puberty is a risk factor for low BMD and previous fractures in young adult men. INTRODUCTION: Peak bone mass (PBM), achieved during puberty, is a determinant of the risk for osteoporosis and future fractures. The role of variations within the normal range in pubertal timing for fractures during pubertal development and for adult bone mass in men is unknown. MATERIALS AND METHODS: The aim of this study was to investigate the importance of pubertal timing for adult BMD and for fractures before achievement of PBM in men. The population-based Gothenburg Osteoporosis and Obesity Determinants (GOOD) study is a well-characterized cohort of young adult Swedish males 18-20 years of age. Detailed growth charts from birth to 18-20 years of age were retrieved for 642 men participating in the GOOD study. Age at peak height velocity (PHV) was estimated and used as an assessment of pubertal timing. The skeletal phenotype was analyzed at young adult age using DXA and pQCT and previous fractures were assessed by questionnaires. RESULTS: Age at PHV was a negative independent predictor of both adult cortical and trabecular volumetric BMD and of total body and radius areal BMD. Moreover, age at PHV was associated with previous fractures in a logistic regression analysis. The OR for cortical osteopenia was 2.49 (95% CI, 1.91-3.24; p