This study examined the effects of Korean red ginseng (KRG) on obese women and aimed to confirm that the effects of KRG on obesity differ dependently on a gene. Fifty obese women were recruited and randomized to receive KRG (n=24) or placebo (n=26) for 8 wk. Measurements of blood pressure, height, weight, waist circumference, waist-hip ratio (WHR), total fat mass, percentage of body fat, resting metabolic rate, basal body temperature, and daily food intake (FI), blood test (serum lipid, liver and renal function), Korean version of obesity-related quality of life scale (KOQOL), and a gene examination were performed. Comparisons of subjects before and after the administration of KRG revealed significant improvements of obesity in terms of weight, body mass index (BMI), WHR, FI, and KOQOL. However, in the comparison between KRG group and placebo group, only KOQOL was significantly different. KRG displayed significant efficacy on BMI and KOQOL in the CT genotype of the G protein beta 3 gene, but not in the CC genotype, on blood sugar test in the Trp64/Arg genotype of the beta 3 adrenergic receptor gene, but not in Trp64/Trp genotype, on KOQOL in the DD genotype of the angiotensin I converting enzyme gene, but not in the ID and DD genotypes. The effects of KRG on obesity were confirmed to some extent. However, a distinct effect compared to placebo was not confirmed. KRG is more effective for improving the secondary issues of the quality of life derived from obesity rather than having direct effects on the obesity-related anthropometric assessment and blood test indices.