Major depression is associated with hypercorticoidism, a risk factor for osteoporosis. However, it is unknown whether depressive disorders are associated with alterations in bone mineral density. The authors measured the density of trabecular bone from the first to the third lumbar vertebra by quantitative computerized tomography in 80 depressed inpatients older than 40 years and in 57 healthy comparison subjects. An analysis of covariance model with age as a covariate showed a significant effect of diagnosis on the dependent variable spinal bone mineral density: depressed patients had lower values. Other factors could not explain the finding. The authors conclude that major depression is a significant risk factor for osteoporosis.