Cancer of the bladder is the seventh most common of all cancers observed in France, and is the second urological cancer after prostate cancer. It is mainly related to nicotine addiction. When doing the initial tests, ultrasound examination of the bladder can enable the clinician to diagnose a polypoid tumour and thus avoid his having to organise diagnostic fibroscopy. When the bladder tumour infiltrates the detrusor muscle, the situation becomes life-threatening for the patient and radical treatment is envisaged. Uro-CT is the standard examination to characterise the lesion and describe its relationship with neighbouring organs. It is essential, and must be performed before endoscopic resection of the tumour, to be correctly interpreted. It is imperative for imaging to look for a synchronous lesion in the upper urinary tract (ureters, renal pelvis), because the presence of such a lesion changes the prognosis of the disease and the sequence of therapy, which is decided by the urologist in a multidisciplinary consultation.