AIM:To clarify the gender differences about the clini-cal features and risk factors of low-dose aspirin (LDA) (81-100 mg daily)-associated peptic ulcer in Japanese patients.METHODS: There were 453 patients under treatment with LDA (298 males, 155 females) who underwent esophagogastroduodenoscopy at the Department of Gastroenterology and Hepatology of Hiratsuka City Hospital between January 2003 and December 2007. They had kept taking the LDA or started treatmentduring the study period and kept taking LDA during the whole period of observation. Of these, 119 patients (87 males, 32 females) were diagnosed as having LDA-associated peptic ulcer. We examined the clinical factors associated with LDA-associated peptic ulcer in both sexes.RESULTS: A history of peptic ulcer was found to be the risk factor for LDA-associated peptic ulcer common to both sexes. In female patients, age greater than 70 years (prevalence ORs 8.441, 95% CI: 1.797-33.649, P = 0.0069) was found to be another significant risk fac-tor, and the time to diagnosis as having LDA-associat-ed peptic ulcer by endoscopy was significantly shorter than that in the male patients (P = 0.0050). CONCLUSION: We demonstrated gender differences about the clinical features and risk factors of LDA-asso-ciated peptic ulcer. Special attention should be paid to aged female patients taking LDA. AIM: To clarify the gender differences about the clini-cal features and risk factors of low-dose aspirin (LDA) (81-100 mg daily) -associated peptic ulcer in Japanese patients. METHODS: There were 453 patients under treatment with LDA ( 298 males, 155 females) who underwent esophagogastroduodenoscopy at the Department of Gastroenterology and Hepatology of Hiratsuka City Hospital between January 2003 and December 2007. They had kept taking the LDA or started treatmentduring the study period and kept taking LDA during the whole period of observation. Of these, 119 patients (87 males, 32 females) were diagnosed as having LDA-associated peptic ulcer. We examined the clinical factors associated with LDA-associated peptic ulcer in both sexes .RESULTS: A history of peptic ulcer was found to be the risk factor for LDA-associated peptic ulcer common to both sexes. In female patients, age greater than 70 years (prevalence ORs 8.441, 95% CI: 1.797-33.649, P = 0.0069) was found to be another significant risk fac-tor, and the time to diagnosis as having LDA-associat-ed peptic ulcer by endoscopy was significantly shorter than that in the male patients (P = 0.0050). CONCLUSION: We demonstrated gender differences about the clinical features and risk factors of LDA-asso-ciated peptic ulcer. Special attention should be paid to aged female patients taking LDA.