Mullerianosis of the urinary bladder is a very rare and morphologically complex tumor-like lesion. It is composed of several types of mullerian-type lesions, including endometriosis, endocervicosis, and endosalpingiosis. This disease occurs in women of the reproductive age group. In the pathogenesis, implantative and metaplastic origins have been suggested, and they are still under discussion. In the present report, a rare case of this lesion in a 41-year-old woman is described. The bladder contained, in addition to typical mullerianosis, glandular cystitis with focal intestinal metaplasia. An interesting and, to our knowledge, hitherto unreported feature was a rare continuity between the glands of mullerianosis and glands of glandular cystitis. The histologic and immunohistochemical findings in the present case support strongly the metaplastic origin of mullerianosis.