Lumbar ligimentum flava obtained from 21 patients of spinal stenosis and 10 patients who underwent surgery for vertebral fracture(control group) were studied with hematoxylin-eosin stain, Verhoff s elastic stain, and immunohistochemical stains for S-100 protein ad fibronectin. The chondroid metaplasia of ligamentum flavum found more frequently and widely in the group of spinal stenosis compared with control group. The elastic fibers were decreased in number and irregu- larly arranged at the bone attached area in the group of spinal stenosis. There was tendency to increase the amount of fibronectin in the stroma of the ligamentum flavum in the group of spinal stenosis. Above findings suggest that chondroid metaplasia and changes of the elastic fiber in the peripheral area of the ligamentum flavum are able to contribute the pathogenesis of spinal stenosis.