Arimidex Multicenter Trial in Growth Hormone (GH) Deficient Boys

Inclusion Criteria: * Growth hormone deficient by formal testing with two provocative agents. * Treated with growth hormone for a minimum of 6 months prior to study entry. * Growth hormone doses must be maintained at 0.2-0.4mg/kg/wk while in protocol. * Stable organic pathology * Presence of puberty \[genital Tanner Stage \> II (\>4cc testicular volume)\] * Bone age (BA) \> or = 11.5 years and \< 15 years Exclusion Criteria: * Participation in any other trial involving hormone therapy for at least 6 months prior. * Chronic illnesses requiring long term medication that impair growth. (Stable patients with occasional asthma, patients on Ritalin or Adderall or patients on topical acne medication may be included). * Hereditary disease diagnosed clinically. * Moderate to severe scoliosis.