The surface features of circulating cells from 5 patients with typical Sezary's Syndrome (SS) are described using scanning electron microscopy (SEM). Sezary cells prepared by different methods, with and without prior fixation in cell suspension, showed similar surface architectures. SS cells were mostly spherical and moderate to markedly villous in appearance, and in this respect, resembled the majority of circulating lymphocytes from patients with chronic lymphocytic leukaemia (CLL). A proportion of cells were larger and more irregular in shape while others had small extensions of cytoplasm resembling small uropods with clusters of polarised microvilli. Despite the latter findings, most SS cells cannot be distinguished from CLL cells on the basis of their surface architecture under the SEM.