Abdominal obesity is associated with blunted GH secretion and a cluster of cardiovascular risk factors that characterize the metabolic syndrome. GH treatment in abdominally obese men reduces visceral adipose tissue and has beneficial effects on the metabolic profile. There are no long-term data on the effects of GH treatment on postmenopausal women with abdominal obesity. Forty postmenopausal women with abdominal obesity participated in a randomized, double-blind, placebo-controlled, 12-month trial with GH (0.67 mg/d). The primary aim was to study the effect of GH treatment on insulin sensitivity. Measurements of glucose disposal rate (GDR) using a euglycemic, hyperinsulinemic glucose clamp; abdominal fat, hepatic fat content, and thigh muscle area using computed tomography; and total body fat and fat-free mass derived from (40)K measurements were performed at baseline and at 6 and 12 months. GH treatment reduced visceral fat mass, increased thigh muscle area, and reduced total and low-density lipoprotein cholesterol compared with placebo. Insulin sensitivity was increased at 12 months compared with baseline values in the GH-treated group. In the GH-treated group only, a low baseline GDR was correlated with a more marked improvement in insulin sensitivity (r = -0.68; P < 0.001). A positive correlation was found between changes in GDR and liver attenuation as a measure of hepatic fat content between baseline and 12 months (r = 0.7; P < 0.001) in the GH-treated group. In postmenopausal women with abdominal obesity, 1 yr of GH treatment improved insulin sensitivity and reduced abdominal visceral fat and total and low-density lipoprotein cholesterol concentrations. The improvement in insulin sensitivity was associated with reduced hepatic fat content.