More than 30 blood group systems have been recognized by International Society of Blood Transfusion (ISBT). ABO blood group is one of the most studied blood group system. ABO blood group system consist of three alleles A, B and O, out which A and B are co-dominant and O is recessive. Many researchers and investigators have found association between ABO blood group and cancer risk. It was found from the recent data that blood group A and AB is associated with increased pancreatic and gastric cancer risk. In the present study data of ABO blood group of 243 patients, both males and females, with confirmed cases of cancer was obtained from Sir Sunderlal hospital, Institute of Medical Science (IMS), Banaras Hindu University (BHU) and Apex hospital, DLW Road, Varanasi. 250 Samples of both males and females were taken as control. Out of 243 cancer patients 117 were males and 126 were females. In 243 cases enrolled in present study, highest number of cases were of breast cancer among women and lowest were rectal cancer. It was found that A blood group was associated with breast cancer, oral cancer, liver cancer and ovarian cancer as compared to other blood group and blood group O was associated with lung cancer, gastric cancer, colon cancer, skin cancer and endometrial cancer.