BACKGROUNDAim of this study is to establish and determine the relationship between the A, B, O blood groups' association with complicated peptic ulcer. MATERIALS AND METHODSThis retrospective study was conducted in a tertiary care centre, Government Vellore Medical College Hospital, on patients who underwent emergency laparotomy for complicated peptic ulcer and gastric perforation from January 2011 to January 2016. One hundred and seventy two (172) male patients were enrolled in the study. And data was collected based on Age wise and Blood group wise distribution of duodenal ulcer perforation and gastric perforation. RESULTSIn 172 patients, all patients were male. In patients with duodenal ulcer perforation, the O blood group association was 45.39% followed by A 36.84%. In patients with gastric perforation, the association with A blood group was 70%, followed by O group 20%. The age of the patients ranged from 11 to 90 years. The incidence of duodenal ulcer perforation was highest in the age group of 31-40 years (31.57%), followed by 41-50 years (23.68%). The highest incidence of duodenal ulcer perforation occurs in Positive group, 141 individuals (92.76%). In gastric perforation, highest incidence was seen in positive group individuals 19 patients (95%). CONCLUSIONAfter interpretation of the data in the study, it was concluded that 1. Gastric perforation was more common in the blood group A. 2. Duodenal ulcer perforation was common in blood group O, followed by blood group A. 3. The incidence of perforation was highest in the age group of 31-40 years. 4. Incidence of gastric perforation was highest in the age group of 61-70 years. 5. Highest incidence of duodenal ulcer perforation as well as gastric perforation was seen in Rh positive individuals (92.76%, 95%).