Patients with primary antibody deficiencies (PAD) are susceptible to recurrent and chronic infections and a variety of complications. This study was performed to assess quality of life (QoL) of PAD patients who were under long term treatment and regular follow-up.Thirty six adults with proved diagnosis of PAD, who had received regular intravenous immunoglobulin replacement therapy, were enrolled in this study. The QoL of selected PAD patients was measured by Medical Outcomes Study 36-item Short-Form (SF-36) Health Survey questionnaire.The patients with PAD showed significantly reduced scores in physical component in comparison with healthy age-sex matched control subjects (60.2±20.1 vs. 85.5±4.7, P<0.001). Mental component score was also significantly decreased in the patient's group (59.8±19.5 vs. 72.3±3.4, P=0.002). There was a reverse association between SF-36 scores and number of infections episodes (r=-0.73 P=0.003). The patients with long delay diagnosis showed significantly lower SF-36 scores (r=-0.62, P=0.003).The patients with PAD who were diagnosed timely and managed appropriately seem to have lower complications and better QoL. However, the patients with severe phenotypes and long delay in diagnosis showed lower QoL, even in medical management.