This study was designed to investigate the short term effects (6 days) of recombinant human (rh) growth hormone (GH) administration (0.056 mg/kg/day) combined with weight training on body composition, exercise and psychological profile and compare it with weight training alone. Previous work has shown an improvement in these parameters in GH deficient individuals (Cuneo et al. 1991a, b), but not trained athletes (Crist, 1988; Irving, 2004). The subjects who took part in this study, were twenty-four self-prescribing weight lifters (rhGH), aged between 20 and 48 years, and the results were compared with twenty-four non-drug-using age-matched exercise controls (EC). The dosages were administered under the supervision of the authors in the morning, before any training sessions and an administration diary was recorded. Group differences were analysed using a two-way (group x time) repeated measures ANOVA. Between-group differences were analysed using an independent t test. Within-group differences were analysed using a paired t test followed by a post-hoc Bonferroni test. Data for psychological profiles were analysed using a non-parametric-related samples t test. Between-group differences were analysed using a Kruskal-Wallis test. Body fat (%) diminished within the rhGH group (19.1 ± 5.1 vs 18.1 ± 5.1 vs 18.2 ± 5.0%, p<0.05) and compared with the EC group (18.1 ± 5.1 vs 22.3 ± 3.3%, p<0.05) and strength (one repetition maximum; bench press (BP) and squat (S)) (BP; 106 ± 18 vs 113 ± 19 vs 112 ± 18 kg; S; 143 ± 27 vs 164 ± 26 vs 163 ± 25 kg, p<0.05) and power (high intensity cycle ergometry) (1345 ± 216 vs 1466 ± 257 vs 1497 ± 253 W, p<0.05) increased within the rhGH group and compared with the EC group (BP; 113 ± 19 vs 97 ± 24 kg; S; 164 ± 26 vs 141 ± 34 kg, p<0.05). A Hospital Anxiety and Depression Scale questionnaire (Zigmond & Snaith, 1983) was significantly decreased in both anxiety (A) and depression (D) symptoms within the rhGH group (A: 6.8 ± 4.5 vs 3.6 ± 3.5 vs 4.1 ± 3.1; D: 4.5 ± 4.7 vs 1.5 ± 2.5 vs 2.5 ± 3.0, p<0.05) and compared with the EC group (A: 3.6 ± 3.5 vs 5.3 ± 2.1; D: 1.5 ± 2.5 vs 3.0 ± 2.8, p<0.05). RhGH administration resulted in an increase in serum insulin-like growth factor (IGF-1) within the rhGH group (164 ± 55 vs 332 ± 91 vs 182 ± 60 ¼mol/l, p<0.05) and compared with the EC group (332 ± 91 vs 169 ± 45 ¼mol/l, p<0.05). In conclusion short term use of rhGH altered body composition favourably, increased strength and power, and improved psychological profiles.