Lymphocyte subsets and K cell activity were evaluated in sickle cell anemia (SCA) and in splenec-tomized patients. Results showed that the number of total lymphocytes, T lymphocyte subsets and B lymphocytes were increased in SCA. However, individuals who had undergone splenectomy did not exhibit all these abnormalities, suggesting that the lack of the spleen apparently was not the unique factor responsible for the lymphocyte abnormalities seen in SCA patients.