Background: The high consanguinity in Middle East increases the risk of genetic diseases, including primary immunodeficiency diseases (PID). Objectives: This study was aimed at determining the rate of positive family history of PID, the overall rate and type of consanguinity, and their effects on delay age during diagnosis of PID. Materials and methods: A retrospective analysis was conducted on 131 children with PID (aged 0 - 14 years) managed at Hamad General Hospital during 1998-2012. Results: Data on 131 patients (75 males & 56 females) of 82 families was analyzed. The most common phenotype of PID was predominantly antibody deficiency (23.7%). The onset age was 24.01 months and delay age 18.7 months. Family history of PID was 66.4% (38.7% in predominantly antibody deficiency and 100% in diseases of immune dysregulation). Positive family history significantly (p = 0.004) reduced the delay age of PID diagnosis by 52.9%. The consanguinity rate was 61.1% (32.3% in the predominantly antibody ID to 96% in the phagocyte defects group), where paternal cousin ranked the highest type (57.5%). Conclusions: This study indicates that family history is common in children with PID and helpful in reducing the delay age. Consanguinity among families of affected children is also high (higher than healthy population). Paternal parallel cousin marriages are the most common type of consanguinity. For a practicing physician, family history is a simple and useful tool