The immuno-hematological aspects of a series of four patients with Sezary Syndrome has been presented. The patients were found to be neither anemic nor thrombocytopenic but marked leukocytosis was noted. The mean and absolute lymphocyte count was % 58 + 18 and 11651 + 6301/mm3 respectively. The peripheral blood smears has revealed of atypical lymphocytes (Sezary Cells) causing leukocytosis. The mean Sezary cell percentage was found to be % 35 + 22.3. When they were studied immunologically they have shown to have a characteristics of T-lymphocytes and they all for¬med T-rosettes with sheep erythrocytes. They have not been sti¬mulated with plant mitogens as well. The serum protein and immu¬noglobulin levels were found to be normal. The chromosomal analysis was obtained on three patients and a marker chromosome (D-14) was seen on one of them. A couple of patients have shown marked elevations of serum lactic dehydrogenase (LDH) level.