Volumetric neuroimaging is increasingly being used by researchers of affective disorders to assess potential involvement of different brain structures in mood regulation and to test neuroanatomic models of mood disorders. In unipolar depression, findings suggest abnormalities in the frontal lobe (particularly the subgenual prefrontal cortex), basal ganglia (particularly the caudate and putamen), cerebellum, and hippocampus/amygdala complex. In bipolar disorder, abnormalities in the third ventricle, frontal lobe, cerebellum, and possibly the temporal lobe are noted. We review the findings for the various regions of the brain, and discuss the implications on the understanding of mood disorders. Directions for future research in volumetric imaging is then discussed.