Three adolescents with severe Crohn's ileocolitis developed osteonecrosis after receiving intravenous corticosteroids and parenteral nutrition, including 10% lipid infusion. Each had achieved clinical remission with therapy. However, several months following completion of therapy, each developed arthralgias and arthritis of weight-bearing and non-weight-bearing joints. Roentgenographic evaluation revealed osteonecrosis involving multiple joints. Osteonecrosis may result from the interference with blood flow to bone and has been produced in animals by infusion of lipid solutions and administration of corticosteroids. We report these cases of osteonecrosis as a probable complication of corticosteroid and lipid infusion in adolescents treated for severe Crohn's disease.