Thirteen cases of angiosarcoma of the face and scalp have been examined using immunohistochemistry and electron microscopy. Endothelial cell markers have been employed in an immunoperoxidase technique on tissue that has either been routinely processed, periodate‐lysine paraformaldehyde fixed (PLP) and cold processed, or fixed in methacarn. A consistent pattern of endothelial cell labelling was only achieved in the PLP fixed tissue. In this fixative the angiosarcomas were factor VIII related antigen negative,Ulex europaeuslectin positive, laminin positive, unlabelled by the monoclonal antibody PAL‐E, and positively labelled by the monoclonal antibody EN4. Ultrastructural examination of four cases showed evidence of vascular lumina in all tumours. Weibel Palade bodies were seen in only one case but three tumours showed some evidence of tight junction formation and marginal folding. Thus, our cell marker studies can be interpreted as consistent with a lymphatic derivation for this type of angiosarcoma but in contra‐distinction the ultrastructural studies showed tumour channels with features suggestive of blood vessel differenti