This is a Phase I/II dendritic cell vaccine study for patients with prostate cancer. Our laboratory has demonstrated that effective tumor immunity in humans is associated with, and likely mediated at least in part by tumor antigen-specific killer T cells (Albert et al., 1998a; Darnell, 1999; Darnell and Posner, 2003). Moreover, we have demonstrated that apoptotic material derived from dying tumor cells are a potent means of delivering antigen to DCs and subsequently triggering tumor antigen-specific T cell responses ex vivo (Albert et al., 1998a; Albert et al., 1998c). In this study, patients with 3 consecutive rises in PSA measured at least 2 week apart, after definite local therapy (prostatectomy or radiation) will be recruited. Peripheral blood monocytes will be collected by leukapheresis and dendritic cells will be generated in the Cleanroom in the Laboratory of Molecular Neuro-Oncology. These dendritic cells will be pulsed with apoptotic prostate cancer cells from a cell line (LNCaP), harvested, tested for certain release criteria, and then injected as vaccine. When patients are found to be eligible for the study, they will be randomized into either the experimental group or the placebo group for the purposes of comparing adverse events between groups only. Vaccine plus 3 boosters (or placebo) will be given, each two weeks apart. After the third booster, patients will be unblinded. Those receiving the vaccine will when enter the follow up phase which includes a post treatment leukapheresis. Those in the placebo group will cross over and receive the vaccine and boosters. The primary outcomes to be evaluated are toxicity and activity. Patients will be evaluated for both local and systemic toxicity. For activity, we measure both immunological and clinical responses to the vaccine, comparing measures taken before and after vaccination, combining patients in both arms.