['To examine different stages of dendritic cells (DCs) in intrauterine (IUPs) and viable tubal (VTPs) pregnancies to further elucidate mechanisms of fetomaternal tolerance and extravillous trophoblast invasion.', 'Experimental study on patient-controlled material.', 'University hospital.', 'Seven women with normal IUPs and ten with VTPs in the first trimester.', 'Suction curettage in IUP, laparoscopy in VTP.', 'Immunohistochemistry for cytokeratin-7 (trophoblast), CD83 (mature DCs), DEC205 (activated but not fully mature DCs), DC-SIGN (immature macrophage-like DCs), and CD14 (macrophages) alone and in double staining.', 'The numbers of CD83+ and DEC205+ cells were similarly low in IUP and VTP (0.83 and 0.44 cells/mm2; 2.28 and 2.96 cells/mm2). The number of DC-SIGN+ cells was higher, though without significant differences among the entities examined (57.5 and 47.4 cells/mm2). About two-thirds of DC-SIGN+ cells were also CD14+ in IUP and VTP.'] Are dendritic cells equally distributed in intrauterine and tubal ectopic pregnancies?