 Study Design: We will conduct a phase II clinical trial in two groups of subjects: men with AIPC who have not yet developed overt metastases Group A, and men with taxane-refractory, metastatic disease Group B. Men in both groups will receive single-agent SU011248 on a six-week repeating schedule, with four weeks of daily treatment followed by a two-week rest. The primary endpoint will be PSA response rate. Secondary endpoints will include time to disease progression, objective response rate, and safety parameters. Eligibility for this study will require signed informed consent, adenocarcinoma of the prostate, documented PSA progression despite ADT, reasonable functional status, resolution of toxic effects from prior treatments, and acceptable bone marrow, hepatic, renal and cardiac function. A Simons two-stage design will be employed to allow early termination for lack of efficacy. Ultimately, 30 patients will be enrolled in each group, for a total of 60 patients. A defined program of history and physical examinations, radiographic studies, and laboratory tests including PSA will be carried out to determine the efficacy and safety of SU011248 in this patient population. 