In 30 melancholic patients and 21 healthy controls, diurnal mood variation was investigated on 3 successive days at 7.30 a.m., 11.30 a.m., 3.30 p.m. and 7.30 p.m. Daily courses with no variation or with a so-called typical variation (morning low, afternoon/evening high) occurred with the same frequency in both samples. Circadian mood variations vary substantially inter- and intraindividually in both depressive patients and healthy controls. However, the controls reported short (ultradian) mood variations more frequently than the patients. Using a semistructured interview, the subjective experience of diurnal mood variations was compared: In melancholic patients, mood variations occur spontaneously in more than half of all cases, whereas healthy controls attribute them almost exclusively to their own activities and/or external circumstances. It is discussed whether ‘typical’ diurnal variations in melancholic patients may have been emphasized in earlier psychopathological literature not because of their frequency but because patients experience the circadian mood rhythm as uninfluenceable.