Interrelations between dysfunctional family interaction and interpersonal problems and eating behaviors as well as psychic impairment are investigated by comparing a non-clinical sample of N = 97 female highschool students to N = 115 patients with anorexia nervosa (AN) and N = 101 patients with bulimia nervosa (BN) of a specialised outpatient unit. 19,7 % of the highschool students showed clinically significant eating behaviors. 32,3 % of the highschoolstudents, 35,5 % of the patients with AN and 48,1 % of the patients with BN had committed non-suicidal self-injurious behaviour at least once. All diagnostic instruments applied were able to differentiate the patients with BN from the patients with AN and the highschool students. Patients with BN showed more impairment by their eating disorder, more psychic symptoms, more dysfunctional family relations and more interpersonal problems than patients with AN and controls. Dysfunctional family interaction, interpersonal problems, and their interaction predicted general psychological strain, eating problems and the relative desired weight in a synergetic way. Self-injurious behavior was best predicted by psychic strain, depending on dysfunctional family and interpersonal relations and their interaction. Patients with AN tend to present themselves and their interpersonal relations in a positive way. Future studies using more specific measurements should re-examine the prevalences of self-injurious behaviours in non-clinical adolescent samples, which is to be focussed more intensely in adolescents as well as eating disorders should.