Children with Turner syndrome (TS) frequently have asymtomatic osteoporosis by radiologic diagnosis. Growth hormone (GH) has been considered as a therapeutic or preventive measure for osteoporosis. GH also has been demonstrated to be effective in improving growth velocity in children with TS. This study was designed to determine the changes In bone density associated with GH therapy. Eight children with TS (45, X in 3; 45, X/46X, Xq in 1; 45, X/46, X, idic(X) In 1; 45, X/46, X, idic(Y) In 1; 45, X/46X, rX(p11q22); and 45, X/46X, iso(Xq) in 1) were studied between chronological ages of 7 to 13 with bone ages of 3 to 11 years. The bone density changes were assessed by dual beam photon densitometry with a program modified for children. The area studied was L2-L4. Bone density was measured every 6 months. Each patient served as her own control for 6 months before GH therapy was started. GH was administered intramuscularly three times weekly at a dosage of 0.125 mg/Kg/dose. Changes in bone density at 6 months of control period was 0.020±1.975 gm/cm2/yr (mean±SEM). During six months of GH therapy changes In bone density was 0.007±0.021 gm/cm2/yr (P > 0.05). This indicates a lack of effectiveness of GH therapy on bone density in children with TS. Further study is required to determine if this lack of effectiveness is because the children were growing or because children with TS may respond differently from the general population.