BACKGROUND: The safety of drinking in patients who have undergone total gastrectomy for gastric cancer has not been established. We conducted a clinical trial to investigate the trend in alcohol absorption in actual patients. METHODS: Patients who received total gastrectomy with lymph-node dissection and Roux-en-Y reconstruction six or more months ago were enrolled. Participants drank 1 unit (20 g) of ethanol within 1 h starting at least 1 h after a meal. The blood alcohol concentration (BAC) was then estimated by a measurement of the breath alcohol concentration. The peak and trend in the BAC in patients was compared with that in healthy volunteers who were matched with patients for the alcohol-sensitive genotype. RESULTS: Ten patients and 10 healthy people were enrolled in the BAC evaluation. The peak BAC (%) was 0.158 in patients after total gastrectomy versus 0.110 in control (P < 0.001). The mean half-life of BAC was 58.0 min in the patient group and 94.0 min in the control group, although the mean time to complete drinking was significantly longer in the patient group than in the control group at 40.8 versus 21.9 min (P = 0.009). CONCLUSION: Drinking alcohol is likely to carry a risk of increasing the BAC in patients who have undergone total gastrectomy.