Corticosteroid therapy may produce alterations in mood. Furthermore, several monoamines, including dopamine, have been implicated in the regulation of mood. We, therefore, examined the relationship between alterations in mood and plasma homovanillic acid (HVA) levels in patients on alternate-day corticosteroid treatment. Although several patients had substantial alterations in mood, there was no significant difference in plasma HVA levels between the on- and off-medication day. Furthermore alterations in depression and anxiety levels were not related to plasma HVA levels. The implications of these findings are discussed.