Bone mineral content and the ultimate compressive strength were determined in 109 fresh lumbar vertebrae from 36 different [human] subjects, 31-79 yr old. Degree of macroscopic disc degeneration and the types of fracture were determined. Three types of fracture (central, wedge and transverse) were found, but only under magnification and at simultaneous movements of the fracture segment. Central type of fracture was found predominantly in specimens with high bone mineral content surrounded by normal discs. Wedge type of fracture was consistent with lower bone mineral content and more severe disc degeneration.