We diagnosed cartilage-hair hypoplasia (CHH) in a female child with prenatal-onset short stature, metaphyseal chondrodysplasia, and severe combined immunodeficiency leading to recurrent, severe respiratory tract infections. The patient required several hospital admissions during her 1st year of life and failed to thrive in spite of antimicrobial therapy and hypercaloric nutrition. Bone marrow transplantation (BMT) from an HLA-identical sister was performed at age 16 months after conditioning with busulphan and cyclophosphamide, using 9 x 10(8) nucleated bone marrow cells/kg body weight. Graft-versus-host disease prophylaxis consisted of cyclosporine and methotrexate. The post-transplantation period was uneventful. She developed full and sustained chimerism as demonstrated by DNA analysis of granulocytes and mononucleated cells on days 44, 69 and 455 post BMT. Cellular immunity was completely reconstituted at 4 months, humoral immunity at 15 months post BMT. The patient is alive and well 24 months post BMT without medication, but the radiological osseous changes persist, and longitudinal growth remains markedly below the 10th percentile for CHH standards; her height at age 3 years 4 months is 66 cm. CONCLUSION: In this patient with unusually severe CHH, bone-marrow transplantation has fully corrected the immune deficiency but has had no influence on the course of the chondrodysplasia.