Several lines of evidence have implicated hypothalamic-pituitary-adrenal (HPA) axis dysfunction in major depression and suicidal behavior. In the present study, the weight and morphology of postmortem adrenal glands were compared between suicide victims and sudden death, nonpsychiatric controls. The mean adrenal weight of the combined left and right glands was significantly higher in the suicide group; this difference was accounted for specifically by increases in left adrenal weight of suicides compared with the control group. There was a positive correlation between adrenal weight and total cortical thickness in both left and right glands, providing direct evidence that increased adrenal weight in suicide victims is due to cortical hypertrophy. The findings of left-right adrenal weight asymmetry in suicides in consistent with the hypothesis of abnormal lateralized input from higher control centers of the HPA axis.