Congenital angiotropic lymphoma (intravascular lymphomatosis) of the T-cell type. The autopsy of a stillborn infant showed an extensive intravascular proliferation of atypical cells throughout the body. There was no infiltration by these cells of the parenchyma of the bone marrow, lymph nodes, or thymus. By histochemistry, these cells were negative for naphthol-ASD-chloroacetate esterase, a marker of granulocytes. By immunohistochemistry, they were reactive with MT-1 and anti-Leu-22, but unreactive with MB-1, L26, anti-Leu-M1, Tu-9, and antihemoglobin antibodies. A few cells reacted with antileukocyte common antigen and UCHL-1. Based on these findings, the lesion was diagnosed as angiotropic lymphoma (intravascular lymphomatosis) of the T-cell type, which occurred congenitally. Most angiotropic lymphomas in the literature are of the B-cell type, and no leukemia virus type I antibody was negative in the mother. 