As part of a collaborative investigation of bladder cancer undertaken in several different clinical facilities, it is proposed that a central laboratory be established for the uniform collection, classification and analysis of pathologic and cytologic materials from participating institutions. Further, it is proposed that this laboratory provide detailed information from the accessioned material to the statistical center of the collaborative clinical studies in order that it can be correlated with etiologic information, tumor characteristics, and clinical course of the disease. It is planned that definitive morphologic studies be carried out in the center seeking pathologic and prognostic factors which, when taken in conjunction with other clinical and laboratory data, would permit the prediction with a high degree of accuracy of the courses of individual patients with bladder cancer following various types of therapy.