Two cases of erythroderma, superficial lymphadenopathy, and abnormal circulating cells similar to Sézary's cells are reported. Skin biopsies of infiltrated lesions in both cases showed the picture of mycosis fungoides. One case regarded as an instance of Sézary's reticulosis eventually revealed a malignant lymphoma, Hodgkin's type, of the lymph nodes, although hematological studies suggested a chronic lymphatic leukemia. Further skin biopsies revealed the picture seen in the tumoral stage of mycosis fungoides or in a reticulum cell lymphoma. The second case had large numbers of monocytoid cells in the blood, and a reticulum cell lymphoma of the lymph nodes. The blood picture was also compatible with the diagnosis of monocytic leukemia. It is suggested that Sézary's reticulosis may not represent a distinct entity, but a syndrome which may be found associated with various neoplastic processes of the lymphoreticular system. The literature on Sézary's reticulosis is reviewed.