Background: One of the most common gastrointestinal surgeries is cholecystectomy. Gallstones are the major causes of cholecystectomy and induce various histopathologic changes. Gallbladder carcinoma is rare with poor prognosis. Metaplasic changes in gallbladder epithelium are considered precancerous lesions. Objectives: This study aimed at revealing the spectrum of histopathological patterns of gallbladder diseases in cholecystectomy specimens. Methods: A total of 1004 gallbladder H & E stained slides of cholecystectomy specimens over one year were studied. Histopathological evaluation was done by 6 pathologists in terms of variables. Results: In our study, the male: female ratio was 1:2.1. The age of patients varied from 17 to 96 years with a mean age of 49.1 years. The mean age of patients with gallstones was 47.52 years and was more common in women. Cholesterol, pigmented, and mixed stones were reported in 58.36%, 39.03%, and 2.6% of gallstones, respectively. The most common histological morphology was chronic calculous cholecystitis (61.18%). The incidence of metaplasia and invasive carcinoma was 19.55% and 0.2%, respectively. Conclusions: In this study, histopathological analysis of gallbladder diseases in the cholecystectomy specimens revealed that chronic calculous cholecystitis was the most common histologic finding. Gallstones were found more commonly in women and cholesterol stone was the predominant type. Pyloric metaplasia was the most frequent type of metaplasia. The rate of invasive carcinoma is compatible with those reported in the literature. Routine histopathological analysis of the cholecystectomy specimens will help to detect incidental carcinoma and precursors of malignancy.