Abstract Background Bowel ischaemia significantly increases morbidity and mortality from adhesional small bowel obstruction. Current biomarkers and clinical parameters have poor predictive value for ischaemia. Our study investigated whether neutrophil‐lymphocyte ratio (NLR) and platelet‐lymphocyte ratio (PLR) could be used to predict bowel ischaemia in adhesional small bowel obstruction. Methods This single‐centre retrospective study collected clinical, biochemical and radiological data from patients with adhesional small bowel obstruction between 2017 and 2020 who underwent operative management. The presence or absence of bowel ischaemia/infarction was used to distinguish two populations. Biochemical markers on admission and immediately prior to operation were collected to give platelet‐lymphocyte ratio (PLR 0 and PLR PRE‐OP , respectively) and neutrophil‐lymphocyte ratio (NLR 0 and NLR PRE‐OP , respectively). SAS 9.4 (SAS Institute Inc., Cary, NC) software was used for data analysis with Mann–Whitney U testing for continuous variables and Pearson Chi‐square test for categorical variables. Sensitivity and specificity for PLR and NLR were calculated by means of receiver operating characteristic (ROC) curve analysis. Results Twenty‐seven patients had intra‐operative bowel ischaemia whilst the remaining 73 had no evidence of bowel ischaemia. Both median PLR PRE‐OP and NLR PRE‐OP were significantly higher in patients with bowel ischaemia compared to those without (PLR PRE‐OP 272 [IQR 224–433] and 231 [IQR 146–295] respectively, P = 0.027; NLR PRE‐OP 12.5 [IQR 8.6–21.3] v. 5.5 [IQR 3.5–10.2] respectively, P ≤ 0.001). Area under the receiver operator characteristic curve (AUC) was 0.762 for NLR PRE‐OP , with a sensitivity of 85.1% and specificity of 63% for NLR 7.4. Conclusion Raised NLR is predictive of bowel ischaemia in patients with adhesional small bowel obstruction.