CONTEXT:: The determinants of serum anti-Müllerian hormone (AMH) levels in adult men remain unclear. OBJECTIVE:: The objective of the study was to investigate the genetic and environmental components in determining postpubertal AMH levels in healthy men. DESIGN AND PARTICIPANTS:: Serum AMH levels, body mass index (BMI), and fat mass (dual energy x-ray absorptiometry) were measured in 64 healthy male (23 monozygotic and 41 dizygotic) twin pairs. RESULTS:: Postpubertal AMH levels were highly genetically determined (broad sense heritability 0.92, 95% confidence interval 0.83–0.96). AMH correlated negatively with BMI (r = −0.26, P = 0.030) and fat mass (r = −0.23, P = 0.048). As AMH, BMI had a high heritability (0.68, 95% confidence interval 0.39–0.83), but no genetic correlation was observed between them. CONCLUSIONS:: AMH levels in men after puberty are under a strong genetic influence. Twin modeling suggests that AMH and BMI are influenced by different sets of genes.