This is a phase II open label single center study that evaluates the activity, efficacy, and toxicity of single agent Tarceva in chemotherapy-naive AIPC patients. Patients will receive single agent Tarceva at 150 mg daily without interruption until disease progression, unacceptable toxicity, or investigator's discretion. Eligible patients are those with documented prostate cancer (regardless of Gleason Score) who are considered hormone refractory as defined below. All patients must fail an anti-androgen withdrawal trial if they were already on such therapy. If patients were on LHRH analogues alone, they must fail the addition of an anti-androgen before being classified as hormone refractory. All patients must have adequate organ functions as specified below and have an ECOG performance status of 2 or less. It is hypothesized that 25 patients will be needed to adequately assess the activity of Tarceva in AIPC.