Mesonephric type adenocarcinoma is a very rare tumour in the bladder and bears a resemblance to nephrogenic adenoma. We report (to the best of our knowledge), the first case where the tumour was partly composed of mesonephric and partly of poorly differentiated transitional cell carcinoma. Staining for alpha 1-antitrypsin and carcino-embryonic antigen were positive in the mesonephric component but negative in the transitional cell carcinoma.