A traditional Korean herbal formula (KH), which is based on Taeumjowi-tang, is currently the most widely used herbal formula in Korea. In this study, KH was administered to obese children for 30 days, and was found to be clinically safe and effective. The subjects were children admitted to hospital to be treated for obesity with relative body weights (%RBW) of 20% or more. Originally, there were 31 subjects, but nine dropped out during the experiment. There were eight girls and 14 boys, whose average age was 11.00 +/- 2.62 years, average weight was 53.37 +/- 17.29 kg, and average period (30-day amount) of KH dosage was 51.18 +/- 22.58 days. The short-term effects of KH on obese children were the reduction of their BMI from 24.34 +/- 3.10 to 23.26 +/- 3.00 kg/m2, of %RBW from 34.41 +/- 10.90 to 25.94 +/- 11.18% (p < 0.01), of body fat mass from 17.99 +/- 5.37 to 16.50 +/- 4.82 kg, and of body fat from 34.16 +/- 3.75 to 32.08 +/- 3.15% (p < 0.01). Concerning anthropometrical measurements, abdominal skin-fold decreased from 26.16 +/- 9.08 to 22.90 +/- 8.35 mm, as did subscapular skin-fold from 20.86 +/- 5.20 to 18.46 +/- 5.31 mm (p < 0.01). In terms of serum lipid levels, which are indices of heart disease, their total cholesterol decreased from 195.38 +/- 31.39 to 183.25 +/- 33.27 mg/dl, the arteriosclerosis index from 4.100 +/- 0.81 to 3.84 +/- 0.64 mg/dl (p < 0.05), and serum leptin level from 14.91 +/- 6.59 to 12.24 +/- 4.98 ng/ml (p < 0.01). Concerning the safety of KH, there were no significant changes in the subjects' livers, hearts, or kidneys. Nor were there any short-term signs of clinically serious side effects or withdrawal symptoms observed. The short-term effects of KH on obese children are weight loss and a decrease in obesity.