A case of malignant lymphoma probably representing the neoplastic counterpart of "monocytoid B cells" is described. The lymphoma cells had medium-sized, oval to indented nuclei and moderate amounts of pale cytoplasm. Immunohistochemical studies on cryostat sections revealed positive staining for pan-B, B1, B4, BA2, 12 (HLA-DR), and IgM lambda, but not T-cell or monocytic markers.