Although the immune system is clearly capable of recognizing and eliminating tumor cells, it usually fails to provide adequate protective antitumor responses. It is becoming increasingly clear that modifications of dendritic cells (DCs), which are central regulators of immune responses, could be a strategy exploited by tumor cells to escape from immune control. This review focuses on the current understanding of DC defects occurring in cancer patients, mechanisms responsible for the induction of such defects, consequences of DC defects on antitumor immune response and current concepts of DC-based immunotherapy. An improved understanding of how tumors interact with DCs to escape from immune control may enable the design of improved DC-based immunotherapeutic strategies for patients with cancer.