Introduction The Cloninger's Psychobiological Model of Temperament and Character includes temperamental dimensions such as reward dependence (RD) and harm avoidance (HA). Studies of RD differentiate between sensitivity to reward (SR) versus to punishment (SP). We investigated the interrelationship between HA and RD in acutely ill patients with binge/purge (B/P) type eating disorders (EDs) and following symptomatic stabilization. Methods Fifty patients with B/P EDs were assessed at admission to inpatient treatment, 36 of whom were reassessed at discharge. Thirty‐six controls were similarly assessed. Participants completed Tridimensional Personality Questionnaire (TPQ), Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), and took the Gambling Task. Results Patients with B/P EDs had higher TPQ‐RD and lower TPQ‐HA accompanied by lower SPSRQ‐SR and SPSRQ‐SP. SPSRQ‐SP correlated positively and negatively with TPQ‐HA and TPQ‐RD, respectively. Conclusions Combination of lower TPQ‐HA, lower SPSRQ‐SP, and greater risk‐taking inclination may maintain disordered eating in patients with B/P EDs. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.