This report describes a rare case of synchronous bilateral carcinoma of the breast in a postmenopausal female patient, with mucinous carcinoma measuring 5 cm in the left breast and multifocal multicentric lobular carcinoma in the right breast. The patient underwent a bilateral mastectomy with adjuvant chemotherapy.To the best of our knowledge, this is the first report of a case of mucinous carcinoma and infiltrating lobular carcinoma coexisting in distinct breasts.