A 5-HT2A receptor promoter polymorphism, -1438G/A, was reported to be significantly increased in patients with anorexia nervosa when compared with controls. In practice, many patients with anorexia nervosa suffer from mood disorders. Furthermore, 5-HT2A receptors are thought to play a role in the etiologies of mood disorders. Thus, we studied the polymorphism in 95 Japanese patients with mood disorders and 106 healthy Japanese controls. The allele frequency for the -1438G/A polymorphism did not differ between the patients and controls. In addition, the genotype frequencies did not differ according to the subdiagnosis, age of onset, family history of psychiatric illness or suicide attempts.