BACKGROUND: The mechanisms underlying the effects of growth hormone(GH) on fat metabolism in GH-deficient (GHD) patients are not fully understood. This study was to evaluate the effects of GH replacement before the body fat changes and their relevant parameters in GHD patients. METHODS: In total, 14 (5 males and 9 females) GHD adults (mean 34.4 +/- 8.2 yr, BMI 23.1 +/- 1.0 kg/m2) received GH treatment for 12 weeks. Body composition by dual-energy X-ray absorptiometry and fasting serum analyses were assessed before and after treatment. RESULTS: GH replacement did not affect body weight (60.9 +/- 3.0, vs. 60.3 +/- 3.3 kg, P = 0.30), body fat mass (19.7 +/- 1.5, vs. 18.4 +/- 1.8 kg, P = 0.10) or HOMA IR (1.65 +/- 0.3, vs. 1.94 +/- 0.4, P = 0.34). However, serum adiponectin and leptin levels were distinctly reduced after GH administration (6.86 +/- 1.2, vs. 5.51 +/- 0.8 mg/L, P = 0.03; 8.7 +/- 1.1, vs. 6.5 +/- 1.0 ng/mL, P < 0.01, respectively). Interestingly, correlations between body fat mass and adipokines were stronger (adiponectin, before r = -0.502, P = 0.07 vs. after r = -0.634, P = 0.02; leptin, before r = 0.378, P = 0.18 vs. after r = 0.711, P = 0.004) after GH administration. CONCLUSION: After 12 weeks-GH replacement, the reductions in serum adiponectin and leptin levels without significant body fat changes and the stronger correlations between body fat mass and these adipokines are reflective of the metabolic effects of GH probably due to the amelioration of compensatory mechanism of adiponectin like GHRH to overcome GH deficiency and leptin resistance in GHD patients.