This trial will evaluate, in patients with metastatic prostate cancer, the tolerability, toxicities, efficacy, and immunologic effects of repeated vaccinations with a recombinant vaccinia virus that contains the Prostate Specific Antigen gene (PROSTVAC). Patients with PSA-expressing adenocarcinoma of the prostate will be evaluated for eligibility that includes a history of prior vaccinia (as vaccine against smallpox) and immunocompetence. We completed a phase I trial investigating the use of rV-CEA in adenocarcinomas of the GI tract, lung and breast. The toxicities encountered are local reactions to the vaccine. We did not encounter any myelosuppression or systemic autoimmune reaction. We would like to evaluate four doses to ensure safety and to decide a best biological dose. Six patients will receive 2.65 x 10(5) PFU and 2.65 x 10(6) PFU of vaccine by scarification. Because higher doses cannot be achieved by scarification, six patients will receive 2.65 x 10(7) PFU and 2.65 x 10(8) PFU subcutaneously. We plan to give three vaccinations at four week intervals. All six patients treated in each dose level must be evaluable for 4 weeks before enrolling patients at the higher dose level. No intrapatient escalation is planned. Toxicity, tumor response, and humoral and cellular immunity factors will be monitored. Optional lymphapheresis will be done on patients that are HLA A2. Once we determined the best biological dose, we would like to accrue an additional 6 patients to that level.