Bladder cancer is a heterogeneous disease with a variable natural history. At one end of the spectrum, low-grade Ta tumors have a low progression rate and require initial endoscopic treatment and surveillance but rarely present a threat to the patient. At the other extreme, high-grade tumors have a high malignant potential associated with significant progression and cancer death rates. In the Western world, bladder cancer is the fourth most common malignancy in men and the eighth most common in women. In Europe and the United States, bladder cancer accounts for 5% to 10% of all malignancies in men. The risk of developing bladder cancer at <75 years of age is 2% to 4% for men and 0.5% to 1% in women compared with the risk of lung cancer, for example, which is 8% in men and 2% in women. For the geographic and temporal comparison of bladder cancer incidence, it is crucial to separate the low-grade from the high-grade tumors. In epidemiologic studies on risk factors for bladder cancer, it is important to distinguish the low-grade Ta tumors from high-grade carcinoma in situ (CIS) and tumors >T1. Current studies do not support the routine screening for bladder cancer. However, prospective long-term studies are required to evaluate the benefits of bladder cancer screening, particularly in those at high risk. After assessing all available evidence, the Epidemiology and Diagnosis Committee has made recommendations on various diagnostic issues, including pathologic evaluation, urinary cytology, and imaging studies. Optimal resection techniques, role of repeat transurethral resection in high-grade T1 tumors, random bladder biopsy, and prostatic urethral biopsy are discussed, and appropriate recommendations are made according to the strength of available evidence.