Primary antibody deficiencies (PADs) are a heterogeneous group of disorders, characterized by hypogammaglobulinemia and increased susceptibility to bacterial infections, leading to hospitalizations. This study was performed to determine the main infectious causes of hospital admissions in selective Iranian patients with PADs. Forty patients with PADs, who were admitted to the Infectious Ward of Children's Medical Center Hospital during a 14-year period, were reviewed in this study. There were 115 documented episodes of hospital admission during a 14-year period. The average length of hospital stay was 33.30 ± 25.72 days. Pneumonia was the most prominent infection leading to hospitalization among these patients (n = 48), followed by gastroenteritis (n = 23). Other less frequent causes of hospitalization were fever and neutropenia, septic arthritis, encephalitis, orbital cellulitis, sepsis, urinary tract infection, meningitis, oral ulcer, and lung abscess. The most common causative organisms of diarrhea were: Giardia lamblia, followed by Candida albicans, and Salmonella sp. Many patients with PADs suffer from repeated infections leading to hospitalization, in spite of immunoglobulin replacement therapy. Respiratory tract infections were the prominent cause of hospitalization among studied patients, followed by gastrointestinal infections.