Dendritic cells (DCs) are specialized antigen presenting cells that link innate and adaptive immune responses. As key mediators of T cell dependent immunity, DCs are considered primary targets for initiating immune responses in infectious diseases and cancer. Conversely, DCs can also play an important role in the induction of tolerance in organ transplantation, autoimmune disorders and allergy. While DCs have been used in clinical trials worldwide during the past decade, many of the highly specialized cell biological characteristics of DCs remain poorly understood. Small numbers of DCs can be isolated as terminally differentiated, post-mitotic cells form either blood or spleen. Alternatively, DC-precursors, such as monocytes or bone marrow-derived stem cells, can be isolated and differentiated into DCs in vitro. The relative low numbers of cells that can thus be obtained, combined with difficulties manipulating these terminally differentiated primary cells in vitro and in vivo, have seriously hampered studies aimed at exploring the cell biology of DCs. Good model cell lines therefore provide invaluable tools to study DC biology. So far most DC models are myeloid leukemia-derived cell lines that can be differentiated in vitro towards a DC phenotype. Here, we compared the phenotypical and functional characteristics of frequently used mouse and human DC-model cell lines. We conclude that, although none of these cell lines fully recapitulates all cell biological or immunological features of primary DCs, some of these cell lines provide valuable tools to study specific aspects of DC biology.