This study aimed to assess the relation between ABO blood groups and the occurrence of familial cancers among the patients with cancer in Kirkuk city, Iraq.<h4>Materials and methods</h4>This cross-sectional study was carried out in Kirkuk city from the period 15th October 2023 to 15th April 2024 on 398 patients diagnosed with cancer in Kirkuk oncology center. The gene discussed is ABO; the disease is cancer.