Purpose: This protocol proposes a safety and feasibility trial in patients with metastatic prostate cancer (stages D1-D3) investigating the induction of antitumor immunity by administration of cultured autologous peripheral blood precursor derived dendritic cells (DC), transfected with mRNA amplified from autologous prostate tumor tissue. The feasibility and dose-limiting toxicity of administering escalating doses of tumor RNA transfected dendritic cells will be defined. As a secondary endpoint, the ability of tumor RNA transfected dendritic cells to induce tumor-specific immune responses will be evaluated. Finally, the anti-tumor effect based on PSA (biochemical) response criteria will be defined.