The authors describe 13 cases of elastofibroma seen by them and review 23 cases from the literature. With the exception of one tumor on the trochanter major, all of the tumors were subscapular. Microscopic and electron-microscopic studies showed that hypertrophy and degeneration of the elastic fibers and lamellae were essential for the formation of the tumor. Histo- and biochemical studies suggested that the fibers were composed of elastin. The fibers were resistant to collagenase but treatment with elastase resulted in a marked decrease in stainability of the fiber substance with elastic stains. Tests for sulphydryl groups were positive. Chemical analysis of one tumor showed 8% elastic and 75–80% collagenous tissue. This investigation indicates that elastofibroma is not a real neoplasm but rather a degenerative pseudotumor of the elastic tissue.