To describe the main characteristics and treatment of autoimmune hemolytic anemia (AHA) in patients with common variable immunodeficiency (CVID), we analyzed data from 18 patients, 4 from an earlier study and 14 from the French DEF-I cohort on adult patients with primary hypogammaglobulinemia. To be included, patients had to have CVID and a previous history of AHA with a hemoglobin level < or =90 g/L at onset. To determine whether AHA is associated with a particular clinical phenotype of CVID, we conducted a case-control study from the DEF-I cohort. The estimated frequency of AHA in CVID patients from the DEF-I cohort was 5.5% (14/252). Median age at AHA diagnosis was 26 years (range, 1-57 yr), and 27.5 years (range, 5-61 yr) at CVID diagnosis. CVID was diagnosed before the onset of AHA in only 2 patients (11%). CVID was diagnosed more than 6 months after AHA in 10 cases (55.5%), and the 2 conditions were diagnosed concomitantly in 6 cases. The 14 patients included in the DEF-I cohort were compared with 238 control patients with CVID but without AHA. Corticosteroids were used as initial treatment for all patients in the current study. An initial response was obtained in 15 of 18 (83%) patients. Overall, 9 of these (60%) achieved a lasting response with steroids alone (7 patients) or in combination with intravenous immunoglobulin (2 patients). Seven patients underwent splenectomy, and 5 additional splenectomies were performed for associated autoimmune thrombocytopenic purpura. After splenectomy, a lasting response was obtained in 3 of the 7 patients with AHA. However, 5 of the 12 splenectomized patients experienced life-threatening infection. Severe infection occurred in 2 of 4 patients receiving immunosuppressive drugs. At the end of follow-up, 13 of 18 (72%) patients were in treatment-free remission (13 complete responses), and 4 of 18 (22%) were in remission while on prednisone < or =20 mg/d. One patient had died, of cancer.