The authors report two cases of primary adenocarcinoma of the urinary bladder with secretion of mucus, observed over a year period, between 1978 and 1990. The different histologic patterns are encountered: mucinous adenocarcinoma (colloid carcinoma), clear cell adenocarcinoma exhibiting glandular and trabecular or papillary patterns. They are often reminiscent of those seen in gastrointestinal tumors. The colloid carcinoma pattern is associated with intense schistosomiasis of the bladder. Macroscopic studies show budding and necrotic tumors, with infiltration and invasion of the musculosa. We agree with the role played by glandular metaplasia of the vesical urothelium that is accepted by the majority of the authors in the histogenesis of these tumors.