Interpersonal problems play a prominent role in the development of binge-eating disorder (BED), so reducing their intensity may be a key focus of many psychological interventions. In recent years, several interpersonal treatments for BED were developed, which posit that binge eating arises to manage relational problems. However, few studies have evaluated the prototypical interpersonal problems, and no studies evaluated the longitudinal changes in interpersonal functioning after treatment within this population. We investigated the severity and prototypicality of interpersonal problems of 101 overweight women with BED from pre-group psychodynamic-interpersonal psychotherapy (GPIP) to 12 months post-GPIP. At baseline, we compared patients' interpersonal problems with two groups of matched controls (46 overweight and 49 normal weight women without a diagnosis of BED) and examined circular correlations between relational problems, depressive symptoms, and binge-eating frequency. Results showed that participants with BED had significantly higher levels of interpersonal problems compared with the matched control samples, with predominantly nonassertive and exploitable styles. Depressive symptoms were related to the presence of friendly-submissive interpersonal problems only among those with BED. Although the intensity of nonassertive interpersonal problems of patients with BED decreased post-group treatment, their profiles remained prototypically nonassertive and exploitable across all time points. Women with BED experience higher levels of interpersonal difficulties exemplified by an exploitable/nonassertive style that significantly improve but continue to prevail even after treatment. Clinicians might modify interventions to focus on increasing interpersonal skills and decreasing interpersonal dysfunctions among those with BED.