This study presents the risk of various cancers in relation to ginseng intake based on the data from a case-control study conducted in the Korea Cancer Center Hospital. Ginseng intakers had a decreased risk [odds ratio = 0.50, 95% confidence interval (CI) = 0.44-0.58] for cancer compared with nonintakers. On the type of ginseng, the odds ratios for cancer were 0.37 (95% CI = 0.29-0.46) for fresh ginseng extract intakers, 0.57 (95% CI = 0.48-0.68) for white ginseng extract intakers, 0.30 (95% CI = 0.22-0.41) for white ginseng powder intakers, and 0.20 (95% CI = 0.08-0.50) for red ginseng intakers. Intakers of fresh ginseng slice, fresh ginseng juice, and white ginseng tea, however, showed no decreasing risk. There was a decrease in risk with the rising frequency and duration of ginseng intake, showing a dose-response relationship. On the site of cancer, the odds ratios were 0.47 for cancer of the lip, oral cavity, and pharynx; 0.20 for esophageal cancer; 0.36 for stomach cancer; 0.42 for colorectal cancer; 0.48 for liver cancer; 0.22 for pancreatic cancer; 0.18 for laryngeal cancer; 0.55 for lung cancer; and 0.15 for ovarian cancer. In cancers of the female breast, uterine cervix, urinary bladder, and thyroid gland, however, there was no association with ginseng intake. In cancers of the lung, lip, oral cavity and pharynx, and liver, smokers with ginseng intake showed decreased odds ratios compared with smokers without ginseng intake. These findings support the view that ginseng intakers had a decreased risk for most cancers compared with nonintakers.(ABSTRACT TRUNCATED AT 250 WORDS)