Objectives: Epidemiologic and auxologic characteristics of patients treated with GH during childhood and adolescence and entered in a national registry in Catalonia were studied between 1988 and 1997. At the end of 1997, prevalence was 53.2 treatments/100,000 inhabitants aged 0–14 years. Maximum annual incidence rates were observed in 1990 and 1991 (34.0–35.6 cases/100,000 inhabitants aged 0–14 years). Study Design: Analysis of treatments terminated in 1993 (n = 548) revealed, for the three principal reasons for cessation of treatment (‘near-final height’, ‘adequate height but further growth potential’, and ‘poor growth response’), that males began and ended treatment at older ages with a better auxologic situation in SDS than girls at the beginning and end of therapy in the first two subgroups, with a similar duration of therapy. Severe GH deficiency (GHD) [both multiple pituitary hormone deficiency (MPHD) and the most severe isolated GHD (IGHD-A)] was more frequent in the group ending treatment at ‘near-final height’, whereas cessation of therapy because of ‘poor growth response’ was more frequent in the group with ‘other causes of short stature’ and no demonstrable GHD by routine tests. In the near-final height group, after excluding Turner’s syndrome, MPHD and GHD cases secondary to brain tumors and GH deficiencies associated with malformative syndromes, positive linear correlations were observed between HSDS at the end of treatment and HSDS at the beginning, predicted adult height SDS (PAHSDS) and target height SDS (THSDS). Multiple regression analysis showed that in this group of patients, 41.4% of the variability in HSDS increment can be explained by the equation: HSDS increment = –0.33 + 0.29 THSDS – 0.68 HSDS at the beginning of treatment. Results: The outcome showed a reasonable use of GH, since good-response cases generally continued treatment until final height whereas therapy was suspended in doubtful cases.