['The role of insulin-like growth factor-1 (IGF-1) in bone health in men is debatable. This study aimed to determine whether IGF-1 is a mediator in age-related decline of bone health status measured by calcaneal speed of sound (SOS) in Malaysian men.', 'The study recruited 279 Chinese and Malay men. Their demographic data, weight, height, calcaneal SOS were taken and fasting blood was collected for total testosterone, sex-hormone binding globulin and IGF-1 assays. The associations between the studied variables were assessed using multiple linear regression (MLR) analysis. Mediator analysis was performed using Sobel test.', 'There was a significant and parallel decrease of IGF-1 and SOS with age (p\u2009<\u20090.05). Serum IGF-1 was significantly and positively associated with SOS (p < 0.05) but after further adjustment for age, the significance was lost (p\u2009>\u20090.05). The strength of the association between age and SOS decreased after adjusting for IGF-1 level but it remained significant (p\u2009<\u20090.05). Sobel test revealed that IGF-1 was a significant partial mediator in the relationship between age and SOS (z\u2009=\u2009-4.3).'] Is insulin-like growth factor-1 a mediator of age-related decline of bone health status in men?