Multiseptate gallbladder is an extremely rare congenital anomaly. We report three cases of this clinical entity. The third patient, a 70-year-old male who was asymptomatic with this condition, also had a gallbladder carcinoma. The three surgically removed gallbladders had multiple thin septa with a honeycomb appearance. Histologically, the septa contained a muscular layer that was continuous with the gallbladder wall. Furthermore, in the third patient, mucinous cystadenoma with focal carcinomatous change in the epithelium was observed. To our knowledge, this is the first description of a multiseptate gallbladder with carcinoma.