Prostate carcinoma is the most common cancer in men and the second most lethal malignancy among the American male population. Nevertheless, it is potentially curable if detected early and treated appropriately. Treatment options vary depending on the extent (stage) of the cancer. MRI has no role as a screening method for prostatic carcinoma because it is expensive, time consuming, and unable to differentiate benign from malignant disease, but it can detect early prostatic cancers in patients with known tumor and can accurately stage these tumors. MRI is becoming the imaging modality of choice for local staging of prostate cancer and is rapidly replacing CT and ultrasonography for this purpose. Treatment protocols for bladder carcinoma also depend on the stage of the tumor. Clinical staging of bladder cancer has been limited. MRI is as good as or better than CT in bladder tumor staging when extravesical tumor involvement is present. MRI also has the potential to become useful in determining the depth of wall invasion in tumors confined to the bladder.