BACKGROUND Our aim is to elucidate causative factors for gallstones, especially focusing on Helicobacter pylori (HP) infection. METHODS We analyzed 15,551 Japanese adults who had no history of gastrectomy, cholecystectomy, HP eradication, and didn't use proton pump inhibitors, anti-diabetic drugs, or anti-cholesterol drugs. 1,057 subjects who previously had HP eradication were analyzed separately. RESULTS Gallstones were detected in 409 of 8,625 men (4.74%) and 285 of 6,926 women (4.11%) by ultrasonography. Among the 25 factors univariately analyzed, age, HP infection, alcohol intake, weight, body mass index (BMI), and 14 blood test values (AST, ALT, ALP, γ-GTP, T-Chol, HDL-Chol, LDL-Chol, TG, TP, Hb, HbA1c, pepsinogen I, pepsinogen II, and pepsinogen I/II ratio) displayed significant association with gallstones (p < 0.05), whereas gender, smoking, height, and three blood test values (Alb, T-Bil, MCV) did not. Multivariate analysis showed that age, gender, alcohol intake, BMI, γ-GTP, LDL-Chol, TP, and HP infection had significant association (p < 0.05). Successive multiple logistic regression analysis calculating odds ratio (OR) and standardized coefficients (β) showed that age (OR/β = 1.57/0.450), BMI (OR/β = 1.30/0.264), HP infection (OR/β = 1.51/0.206), lower alcohol intake (OR/β = 1.33/0.144), γ-GTP (OR/β = 1.15/0.139), and pepsinogen I/II ratio (OR/β = 1.08/0.038) have significant positive association with gallstones, whereas gender does not. The gallstone prevalence among HP-negative, HP-eradicated, and HP-positive subjects was 3.81, 4.73 and 6.08%, respectively. The matched analysis controlling age, BMI, γ-GTP, alcohol intake, pepsinogen I/II ratio and gender also demonstrated that gallstone prevalence among HP-eradicated subjects was significantly lower compared with HP-positive subjects (p < 0.05). CONCLUSIONS HP infection is positively associated with gallstones. HP eradication may lead to prevention of gallstones.