In this article the contribution of neuropsychological research for a better understanding of the psychopathology of mood disorders is reviewed. First, the broad spectrum of bipolar disorders is described. Second, a selective review of important results of neuropsychological studies with patients with mood disorders is presented. Although several methodological problems limit the interpretation of the findings, there is evidence that patients with a bipolar disorder show a consistent impairment in attention, memory/learning and executive functions. The cognitive deficits are still visible during clinical recovery (euthymia) and closely associated with psychosocial limitation in daily life. Finally, the impact of neuropsychological findings is considered in relation to assessment, treatment and prognosis.