We examined the association between the tryptophan hydroxylase 1 (TPH1) gene and eating disorders focusing on obsessionality.The sample included 62 women with a lifetime diagnosis of anorexia nervosa (AN) as well as 50 women with a lifetime diagnosis of bulimia nervosa (BN) recruited from specialist clinics for eating disorders and 131 healthy women in Korea. Blood samples were collected from all participants for the TPH1 genotyping. The patients were ad ministered the Korean version of the Eating Disorders Examination and obsessionality was conceptualized using measures of persistence, harm avoidance, and obsessive-compulsive symptoms.In the case-control comparisons, the frequency of the A/A genotype was increased in the patients with BN, but this difference was not significant after correcting for multiple testing. We found no effect of the TPH A218C polymorphism on obsessionality in the patients with AN or BN.Although the present findings should be regarded as preliminary because of the small size of our sample, they suggest that the TPH1 gene may contribute to the genetic susceptibility to BN and be associated with the other unexplored traits of bulimic case status.