AIM: To investigate the incidence of gastrointestina symptoms and the nature of consequent utilization o health care services in a Japanese population. METHODS: Using self-report, we conducted a prospective cohort study of a nationally representative sample of the Japanese population over a one-month period to determine the incidence of gastrointestina symptoms of all kinds and resultant health care utilization. Both information on visits to physicians and use of complementary and alternative medicine therapies were collected. RESULTS: From a total of 3568 in the recruitmen sample, 3477 participants completed a health diary (response rate 97%). The data of 112 participants with baseline active gastrointestinal diseases were excluded from the analysis, leaving 3365 participants in the study The incidence of gastrointestinal symptoms was 25% and the mean number of symptomatic episodes was 0.66 in a month. Abdominal pain, diarrhea, nausea, constipation and dyspepsia were the most frequent symptoms Female gender, younger age, and low baseline quality o life were risk factors for developing these symptoms. The participants were more likely to treat themselves, using dietary, complementary or alternative medicines, than to visit physicians, except in the case of vomiting.CONCLUSION: Gastrointestinal symptoms are common in the Japanese population, with an incidence of 25%. Abdominal pain, diarrhea, nausea, constipation and dyspepsia are the most frequent symptoms. Risk factors for developing these symptoms include female gender, younger age, and low baseline quality of life. AIM: To investigate the incidence of gastrointestincies and the nature of consequent utilization o health care services in a Japanese population. METHODS: Using self-report, we conducted a prospective cohort study of a nationally representative sample of the Japanese population over a one- all information on visits to physicians and use of complementary and alternative medicine therapies were collected. RESULTS: From a total of 3568 in the recruitmen sample, 3477 participants completed a health diary (response rate 97%). The data of 112 participants with baseline active gastrointestinal diseases were excluded from the analysis, leaving 3365 participants in the study The incidence of gastrointestinal symptoms was 25% and the mean number of symptomatic episodes was 0.66 in a month. Abdominal pain, diarrhea, nausea, constipation and dyspepsia were the most frequent The symptoms were female gender, younger age, and low baseline quality o life were risk factors for developing these symptoms. The participants were more likely to treat themselves, using dietary, complementary or alternative medicines, than to visit physicians, except in the case of vomiting. CONCLUSION: Gastrointestinal symptoms are common in the Japanese population, with an incidence of 25%. Abdominal pain, diarrhea, nausea, constipation and dyspepsia are the most frequent symptoms. Risk factors for developing these symptoms include female gender, younger age, and low baseline quality of life.