Anorexia nervosa is a severe disorder which seems likely to have a multifactorial aetiology. However, several studies have stressed that genetic factors play a significant role. Epidemiological studies have shown that the lifetime risk for first-degree relatives of a patient with an eating disorder is 6% compared to 1% among relatives of controls, and a twin study performed on 34 pairs of twins has shown a higher concordance rate in monozygotic twins (55%) compared to dizygotic twins (7%). The vulnerability component of anorexia nervosa that can be attributed to genetic influences has been estimated from twin studies to be around 70%. Despite this, few genetic studies have been performed testing the role of candidate genes which code for proteins potentially implicated in the aetiopathogenesis of the disorder. In this review, genes encoding components of the dopamine, serotonin, opiate, and noradrenaline systems are assessed for their role in anorexia nervosa. Attention is paid to psychological dimensions, clinical symptoms, co-morbidity frequency, pharmacological data, and biological measures that characterize anorexia nervosa.