We examined the relationship between moderate obesity and glucose metabolism, insulin sensitivity and suspected fatty liver in children. We measured body mass index (BMI), z-score BMI, caliper skinfold thickness, waist and hip circumference in 94 participants (mean age 9.7 +/-2.2 years). Fasting blood glucose, insulin, HOMA score, lipid profile and transaminases (ALT, AST) were measured. Fatty liver and skinfold thickness were evaluated by means of ultrasound. The z-score BMI was 2.01 +/-0.39 (mean +/- SD), and the duration of obesity was 4.3+/-3.03 years. A positive correlation was found between caliper and US skinfold thickness for tricipital (r= 0.33; p= 0.003) and sovrailiac skinfold (r= 0.34; p=0.003). Fatty liver was diagnosed in 64% of children and it was positively related to anthropometric measurements. The three sub-groups--group 0 (normal US liver and normal transaminases); group 1 (US fatty liver and normal transaminases); group 2 (US fatty liver and elevated transaminases)--showed a difference concerning z-score BMI, insulin and HOMA parameters (Tukey test: z score BMI group 1 vs group 0 and 2 vs group 0; serum insulin: group 2 vs group 1 and group 2 vs group 0; HOMA IR: group 2 vs group 1 and group 2 vs group 0). Moderately obese children with steatosis exhibited a clear increase of insulin and insulin resistance which represents indices of a future metabolic syndrome. In addition, it is important to perform a liver ultrasound since transaminases seems to be not adequate for the diagnosis of fatty liver.