Basal and stimulated serum growth hormone (GH) levels after exercise, insulin induced hypoglycemia (IIH) and oral clonidine were evaluated in 20 (16 M, 4 F) normal statured obese (body mass index greater than or equal to 25 kg/M2) children. Basal serum GH levels (mean +/- SEM, 2.0 +/- 0.38 ng/ml) were not different from basal levels in non-obese children. The mean peak levels were 3.16 +/- 1.17 ng/ml, 2.15 +/- 0.36 ng/ml and 3.15 +/- 1.12 ng/ml (+/- SEM) after exercise, IIH and oral clonidine, respectively. The positive responses (peak level of serum GH greater than 7 ng/ml) were seen in 10% with exercise, in 10% with clonidine and in none with IIH test. These observations suggest that GH response to oral clonidine is subnormal in obese children.