Osteoporosis (OP) is a growing health problem not only in women but also in men. It is well known that men lose bone during aging and are at risk for OP , but the risk factors for OP in men remain controversial. To assess determinants of bone mineral density (BMD) in the spine and femoral neck, 37 healthy men aged 43-73 years were measured using dual photon absorptiometry. Predictors of lumbar spine and femoral neck BMD were determined using multiple linear regression analysis. Backward elimination procedure was used to identify variables significantly related to BMD. The independent variables entered the regression model included age; body mass index (BMI); smoking history; alcohol intake; urinary calcium and hydroxyproline; and serum concentrations of osteocalcin, parathyroid hormone, testosterone, growth hormone, and cortisol. Backward regression analysis indicated that testosterone, cortisol, and BMI were significant predictors of BMD in the lumbar spine while testosterone, hydroxyproline, and osteocalcin were significant predictors of BMD in the femoral neck. Testosterone, cortisol, and BMI accounted for 44% of the total variance in lumbar spine BMD, and testosterone, hydroxyproline, and osteocalcin accounted for 20% of the total variance in femoral neck BMD. These observations suggest that testosterone, cortisol and BMI are determinants of lumbar spine BMD, while testosterone, urinary hydroxyproline, and osteocalcin are determinants of femoral BMD in healthy men.