Abstract: Objective To investigate the clinical and immunological characteristics, treatment and prognosis of common variable immune deficiency (CVID) in adult patients. Methods We retrospectively analyzed the clinical data of 13 adult patients hospitalized in our hospital for CVID diagnosed according to the criteria in International Consensus Document (2016), and analyzed their clinical manifestations, laboratory test results, imaging findings, pathological examinations and treatments. Results The mean age of onset was 24.46±16.82 years in these patients, who had a mean age of 32.54±14.86 years at diagnosis with a median diagnostic delay of 5 years (IQR: 2-15 years). The main manifestation of the patients was repeated infections, including repeated respiratory tract infection (10 cases; 76.9% ) and repeated diarrhea (3 cases; 23.1% ). Three (23.1% ) of the patients had autoimmune disease and 10 (76.9%) had chronic pulmonary disease. IgG, IgA and IgM were decreased in all the patients. The proportion of CD4+ T cells decreased in 10 patients (76.9%), CD8+ T cells increased in 11 patients (84.6%), and CD4/ CD8 decreased in 10 patients (76.9% ). Complement C3 decreased in 58.3% (7/12) and C4 decreased in 33.3% (4/12) of the patients. Twelve patients (92.3% ) were treated with intravenous infusion of gamma globulin with symptomatic treatments. One patient died due to massive gastrointestinal hemorrhage, and the other patients showed improve ments after the treatments and were discharged. Conclusion The clinical manifestations of CVID are diverse, and recurrent respiratory tract infection is the most common manifestation. Decreased IgG often accompanied by lowered IgA and IgM levels is a common finding in laboratory tests. The treatment of CVID currently relies on gamma globulin with symptomatic treatments for the complications.