A 49‐year‐old woman presented with a long history of depressive symptoms and frequent exacerbations despite adequate trials of pharmacotherapy. On evaluation, she was found to have recurrent major depression as well as severe verbal memory deficits. Magnetic resonance imaging revealed a large left frontal cyst with bony erosion and some mass effect on the cortex. Intracranial (arachnoid) cysts are rare and their psychiatric significance has often been minimized. However recent reports have associated temporal lobe cysts to psychotic symptoms. This case is discussed in view of these studies as well as findings linking left frontal lobe pathology to depression. Depression 1:275–277 (1993). © 1993 Wiley‐Liss, Inc. Copyright © 1993 Wiley‐Liss, Inc., A Wiley Company