Central serotonin pathways modulate eating patterns, and may also participate in the regulation of behavioral impulsivity and mood. Recent studies lend support to the hypothesis that impaired postingestive satiety in bulimia nervosa is associated with reduced hypothalamic serotonergic responsiveness. Serotonin dysregulation has been implicated in major depression, and may play a role in the increased prevalence of depressive episodes in patients with eating disorders. This review compares evidence for alterations in central serotonin regulation in patients with anorexia nervosa, bulimia nervosa, and depression. It is proposed that impaired synaptic transmission in functionally distinct serotonin pathways may result in concurrent or sequential periods of binge eating, behavioral impulsivity, and depression in patients with eating disorders.