Several lines of evidence suggest disturbances of serotonin (5-HT) and dopamine (DA) pathways play a role in the pathogenesis and pathophysiology of anorexia nervosa (AN) and bulimia nervosa (BN). Studies using imaging with radioligands specific for 5HT and DA components, have found alterations of the 5-HT1A and 5-HT2A receptors, and DA D2/D3 receptors in AN and BN. In addition, some studies suggest relationships between these components and traits often found in individuals with AN and BN, such as harm avoidance and drive for thinness. Moreover, subtypes may have different patterns of 5-HT-DA dysfunction which may shed light on understanding specific symptoms such as inflexibility and rigidity and disregard of normal rewards in AN, or unstable mood and impulse dyscontrol in BN. The 5HT and DA systems are highly complex. Thus disturbances of these components may reflect dysregulation of these neuronal systems, rather than identify the exact etiology. In summary, new technologies such as PET and/or fMRI offer the promise of understanding the relationship of behavior and neurocircuits contributing to ED. Futhermore PET and radioligand studies may be a useful tool for investigating and managing medication response in treatment resistant individuals.