PURPOSE: Polyps and polypoid lesions of the gallbladder are now increasingly detected. However the nature of disease is hard to define before operation and the indications for surgical intervention remain controversial. We attempted to differentiate between benign polyps and neoplastic lesions by comparing their clinical data and pathological findings. METHODS: The study comprised 128 consecutive patients who underwent resection for polypoid lesions of the gallbladder. The lesions were classified into five groups histologically, and the clinico-pathological characteristics were compared among the groups. RESULTS: We found cholesterol polyps in 42 patients, inflammatory polyps in 13, adenomyomatoses in 14, adenomas in 15, and carcinomas in 44. The mean age of the patients with carcinoma, all of whom were over 40 years, was significantly higher than that of the other groups (P<0.05). Carcinoma patients showed a female preponderance. The incidences of gallstones and presenting symptoms were not different between the benign and malignant diseases. The mean diameters of cholesterol polyps and inflammatory polyps were less than 5 mm, those of adenomyomatoses and adenomas were around 1 cm, and that of carcinoma was over 2 cm (P<0.05). Most of the benign polyps were pedunculated, but sessile lesions were more frequent in the malignant polyps (P<0.05). Neoplastic polyps tended to be single. CONCLUSION: It is suggested that polypoid lesions of the gallbladder should be removed surgically when the lesion exceeds 1 cm in diameter, is single in number, or is sessile. The possibility for malignancy should be considered if the patient is female, and over 40 years of age.