We reviewed the clinical features of 100 cases of the sickle cell chest syndrome in 57 pediatric patients hospitalized with radiographic findings of pulmonary or pleural disease. Pulmonary infiltration was more common in the lower lobes (86%) than in the upper (25%) or middle lobes (22%). Pleural effusions were present in 38% of cases. Chest syndrome was recognized on presentation in 79% of cases, but was recognized only later in 21% of patients admitted for other indications. Patients recognized initially were more often febrile on admission (68%) than were subsequently recognized patients (33%) (p < 0.01). but fever eventually occurred in 99 of 100 cases. Pain was an antecedent or coincident problem in 67% of cases. Median hospital stay was 7 days in those 58 cases in which narcotics were given, but only 4 days in those 42 cases in which narcotics were not administered (p < 0.001). Polyvalent pneumococcal vaccine had been administered to 44 of our 57 patients at some time before their hospitalizations and 18 patients had been on oral penicillin prophylaxis. Blood was cultured in 93 cases and in only two instances grewStreptococcus pneumoniae.Serologic evidence ofHemoplulus influenzaetype b infection was found in two additional patients. We conclude that the sickle cell chest syndrome is an acute febrile pulmonary disease frequently associated with pain and/or narcotic analgesic therapy but infrequently associated with proven bacterial infection.