Over the past ten years, the identification of the critical role that dendritic cells (DCs) play in stimulating a specific immune response has led to their use in cancer and HIV therapy. Interesting responses have been reported but the most effective approach and the duration of these responses are still unclear. The quality of DCs, the means by which tumor antigens are delivered to DCs and the problems associated with monitoring the immune response have made individual studies difficult to compare. Much work is still needed to determine the role that DC-based cancer vaccines will have, the most effective way to deliver DCs to patients and the most relevant antigens to provide to DCs.