The authors relate five cases of primary adenocarcinoma of the bladder that occurred between 1977 and 1983. Four tumours were located in the base and the lateral sides of the bladder, while the fifth was in the dome. Four tumours out of five were invading when diagnosis was done and were cured by a wide surgical cutting-away; the fifth which was a superficial one, was stopped by endoscopic resection. Bladder primary adenocarcinoma represent less than two percent of the whole epithelial tumours of this organ. They can be found under two specific topographic aspects: the first one, located in the dome or in the anterior wall is considered as a tumour of urachus, the second one, usually located in the trigonal and peri-trigonal area is considered as a vesical adenocarcinoma proper. The histogenesis of these lesions quite probably lies in a mechanism of vesical urothelium metaplasia under the influence of mechanical and infectious factors. Most of these tumours are isolated and invading when they are found out. One might distinguish adenocarcinomas similar to those of the gut, from urothelial carcinomas where the metaplastic glandular features are predominant. Clinically, glandular tumours hardly differ from the usual urothelial invading carcinoma except by a mucus secretion in the bladder that is, however quite unusual. Prognosis of such lesions is bad but a little better in urachus carcinoma cases. The treatment is surgical and involves a wide cutting-away, the extent of which can be discussed for urachus tumors. The impact of radiotherapy and chemotherapy upon them has still to be proved.(ABSTRACT TRUNCATED AT 250 WORDS)