The GH/IGF-I axis function are reported to ameliorate after weight-loss. Bariatric surgery leads to a significant weight loss in morbidly obese patients. We investigated the relationships between GH/IGF-I axis and body composition in 20 morbidly obese females (BMI: 44.8±4.7; waist circumference (W) 119.5±7.2 cm, age 33.7±11.7 yrs) with a normal glucose tolerance, before and after laparoscopic silicone adjustable-gastric banding (LASGB). The GH axis was evaluated by GH response after GHRH+arginine test and IGF-I levels. Patients were evaluated 6 months after surgery and a well balanced mildly hypocaloric diet. Fat Mass (FM), Free Fat Mass (FFM) were evaluated by bioimpedance analysis. Before surgery, 8 (40%) subjects were GH deficient (peak GH<4.2 μg/l), while 7 (35%) had IGF-I levels below the normal values for age and sex. Postoperatively, GH response was persistently impaired in 3 (15%) subjects, while IGF-I levels were still reduced in 9 (45%). After 6 months BMI, W, FM (P<0.001) and FFM (P=0.03) were significantly reduced. The percent decrement of FM was greater than that of FFM (22.4±16% vs 5.6±2.3%; P<0.001). GH response was persistently impaired in 3 (15%) subjects, while IGF-I levels were still reduced in 9 (45%). In addition, a significant correlation was found between the decrement of FFM (r=0.81; P<0.001) and that of FM (r=0.47; P<0.04) and the decrement of IGF-I. At the multiple regression analysis, the percentage of FM and W at baseline were the major determinants of IGF-I. In conclusion, both the nutritional status and a relative malabsorption might affect IGF-I and FFM. After bariatric surgery and after the initial acute negative energy balance, a persistent deficiency in GH/IGF-I axis is present and this particular endocrine profile is also associated to unfavourable body composition changes. The low IGF-I levels might represent a possible marker of an underlying persistent catabolic state in these subjects.