(18)F-fluorodeoxyglucose (FDG) is the most common positron emission tomography (PET) radiotracer used in prostate and bladder cancer evaluation, but its role is hampered by a generally low glucose metabolic rate in primary prostate carcinoma, and physiological excretion of FDG through the urinary system masking FDG uptake in primary bladder and prostate carcinoma. FDG-PET may have a role in selected patients for staging and restaging advanced prostate cancer, particularly in patients with an increasing prostatic-specific antigen (PSA) level. The use of diuresis strategies facilitates the identification of primary bladder cancer, and may be useful in staging extravesical spread of disease. FDG-PET may also be useful in patients with ureteric and urethral cancers. New PET tracers are showing promise in the staging and biological characterization of prostate cancer, which can assist with therapeutic decision making in patients undergoing radiotherapy of primary disease, and in the assessment of metastatic disease.