Dendritic cells which are the most effective cells in the primary immune response are the members of antigen presenting cells. The name “dendritic” was originated from the word “dendron” which means tree since these cells have long cytoplasmic branching processes. Dendritic cells constitute approximately 0.1 to 1 percent of the blood mononuclear cell population. Dendritic cells play a primary role in antigen capture and T cell stimulation. In this review article the structure and function of dendritic cells and their roles in infections were reviewed.