Silent ulcers can induce life-threatening complications, like hemorrhage or perforation, and still represent a clinical challenge. Few studies have implicated that NSAID use and old age might characterize painless ulcer.(BMJ 1988; 297:833, Am J Gastro 1997; 92:1289). The exact prevalence of silent ulcers has not yet been established. The aim of this study was to investigate the prevalence of painless ulcer and compare the demographic, clinical and endoscopic features between painful and painless ulcers. Methods: From Jan. to Nov. 1999, a prospective screening esophagogastroduodenoscopy (EGD) was consecutively conducted in 3,626 Chinese subjects who received a paid hospital physical check up. Those who were asymptomatic and having EGD findings of either gastric ulcer (GU) or duodenal ulcer (DU) were enrolled in the painless group. The patients in control group were consecutivly selected from the painful ulcer patients in our outpatient clinic. The following factors were compared between the two groups: age, gender, body mass index (BMI), blood type, smoking, alcoholism, habitual tea or coffee drinking, past history of peptic ulcer disease(PUD), hypertension (HT) or diabetes mellitus (DM), ulcer activity, position and size, and status of Helicobacter pylori(HP). Results: 1) 223 (6.1%, M/F=155/68) and 263 subjects (7.2%, M/F=185/78) had asymptomatic GU and DU, respectively. While 253 (M/F=190/63) and 231 (M/F=143/78) patients have painful GU and DU in control group. 2) Asymptomatic GU had younger age (58.1±13.0 vs.63.0±14.7 yrs, p<0.05), higher BMI (24.7±3.5 vs. 23.4±3.7, p<0.05), smaller ulcer size (63.2% vs.35.2%, with ulcer size ≤ 1cm, p<0.01), less active ulcer(57.3% vs. 72.5%, in active stage, p<0.01), less usage of NSAID (5.4% vs. 11.5%, p<0.05), and higher percentage of habitual tea-drinking (38.6% vs. 23.3%). 3) The asymptomatic DU had higher BMI (24.3±3.2 vs. 22.9±3.2. p<0.05), smaller ulcer size (71.5% vs. 44.3%, with ulcer size ≤ 1cm, P<0.01), less active ulcer(43.3% vs. 72.0%,in active stage, P<0.01), and higher percentage of habitual tea-drinking (38.0% s. 29.9 %, p<0.05). 4) No differences were found between painful and painless ulcers in: gender, blood type, smoking, alcoholism, habitual coffee drinking, ulcer position, history of PUD, HT or DM, and status of HP. Conclusions: The subjects with silent peptic ulcer tended to have higher BMI, habitual of tea-drinking, and smaller ulcers in healing stage. In contrast to previous reports, the usage of NSAID and old age may not be the factors featured the asymptomatic GU.