Mucosa-associated lymphoid tissue (MALT) lymphomas arise in most cases in the gastrointestinal tract, and are usually of low-grade B cell origin. MALT lymphomas may rarely occur in organs where lymphoid tissue is sparse, especially following inflammatory conditions. Primary lymphomas of the gallbladder are extremely rare, and MALT lymphoma has been reported only twice. We herein describe the third case of low-grade MALT lymphoma of the gallbladder, which exhibits an unusual clinical behavior. The exceptionally advanced stage of the disease stresses the importance of early operation when cholecystectomy is indicated.