The Tridimensional Personality Questionnaire (TPQ) was developed to measure a variety of personality variants on three biosocial dimensions, harm avoidance (HA), novelty seeking (NS), and reward dependence (RD), which are thought to be related to serotonin (5-HT), dopamine (DA), and norepinephrine (NE) function, respectively. Patients with eating disorders have been reported to have abnormalities in all of these systems, as well as personality variants described by these dimensions. We therefore administered the TPQ to 147 patients with DSM-III-R defined eating disorders (110 bulimia nervosa [BN], 27 with anorexia nervosa [AN], and 10 with BN+AN) and compared their scores to those of 350 female controls. When significant, post hoc Bonferroni t tests were performed using alpha = 0.05. All subtypes of eating disorder patients scored significantly higher on HA than controls (p < or = .0001, analysis of variance. Only patients with BN (+/- AN) had significantly higher degrees of NS (p < or = .0001), particularly on the impulsiveness subscale (NS2), although this may, in part, be due to age. No significant differences in total RD were found, although BN patients scored lower on RD3 (attachment vs. detachment) and higher on RD4 (dependence vs. independence) than controls. In addition, AN patients had significantly higher RD2 (persistence vs. irresoluteness) subscale scores. These data support a theory of 5-HT dysregulation in both types of eating disorders and suggest that further research be done on the role of DA and NE in BN.