The molecular basis for Marfan's syndrome is known to reside in mutations in FBN1, the gene for fibrillin 1. The skeletal manifestations of Marfan syndrome include morphologic abnormalities and osteopenia. Presence and distribution of fibrillin 1 in adult bone (healthy or with Marfan syndrome) has not been studied extensively. We evaluated distribution of fibrillin and type III collagen in bone and cartilage of children and adults without bone disease, using monoclonal antibodies. Fibrillin is mostly present in attachment sites for tendons. In cartilage and bone tissue, fibrillin is identified at the junction between cartilage and bone in children, and in the areas with intense osteoblastic activity. These data suggest participation of fibrillin in bone formation and growth during youth and in bone mineralisation in adult.