This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. Treatment of bladder cancer presents a serious and often perplexing problem to the urologist. From five different modes of surgical treatment and a minimum of three techniques of radiation therapy, he must select one which is suitable for the general condition of the patient having a bladder cancer of specific stage of infiltration, specific cell type, degree of cellular differentiation, size, and location within the bladder; and he must consider whether there are single or multiple lesions. Some of these factors have greater weight than others in determining the type of treatment and curability. The stage of infiltration of the bladder wall with a malignancy is, without doubt, the single most important factor. Many characteristics associated with infiltration and spread of tumor cells within the bladder have been observed and reported. Certain of these will be discussed subsequently as they apply to clinical, surgical, and histologic staging. Data concerning staging