Objectives: Studies of growth hormone (GH) effectiveness in prepubertal children with cystic fibrosis (CF) have been published previously. We present a retrospective study of GH treatment in adolescents with CF. Study design: We performed a retrospective evaluation of data from 25 pubertal adolescents (ages 13 years 4 months to 16 years 11 months, Tanner stage III or IV). Thirteen (4 F) were followed for 1 year, then received 1 year of treatment with GH (GHTX). We compared the results with a 'control' group of 12 (4 F) whose growth was followed for 1 year (NonTX) but who were not treated with GH at the time of this review. Anthropometric data included: height, weight, lean tissue mass (LTM) and bone mineral content (BMC). Pulmonary function, number of hospitalizations, glycosylated haemoglobin (HbA1c), random blood glucose levels, IGF-I, oestradiol and testosterone levels are also reported. Results: There was no difference between the groups at baseline. After 1 year, GHTX had significantly greater height and weight velocity, height and weight Z-scores, body mass index (BMI), LTM and BMC. Absolute pulmonary function was better and hospitalizations were fewer in the GHTX. No subject developed glucose intolerance or had any other side-effects. Conclusion: These results suggest that GH use in pubertal adolescents with CF safely improves height, body weight, bone mineralization and clinical status.