Sir.—Theoretically, in patients with sickle cell anemia who autosplenectomize by age 4 to 5 years a compensatory hyperplasia of other lymphoid organs may develop, particularly in the tonsils and adenoids. If so, symptoms associated with tonsillar hyperplasia should occur more often in patients with sickle cell disease than in normal children. Enlarged tonsils and adenoids are the most frequent cause of sleep apnea syndrome in pediatric patients.1 If tonsillar and adenoidal hypertrophy is more common in patients with sickle cell disease than in children without the disease, the symptoms of sleep apnea syndrome (eg, snoring and daytime sleepiness) should occur more frequently in them than in children without this disease. Since hypoxemia is poorly tolerated by patients with sickle cell anemia, sleep-related apnea in this population could produce much greater morbidity than in children with normal oxygen transport. In particular, sleep-related hypoxemia could possibly precipitate the various acute