Background: The present study examined the impact of surgeon specific differences on the postoperative systemic inflammatory response (SIR) as measured by postoperative C-reactive protein (CRP), and complications, following elective surgery for colorectal cancer. Methods: 684 patients who underwent elective colorectal cancer resection performed by 10 consultant surgeons at single centre between 2008 and 2016 were included. Exceeding the established C-reactive protein (CRP) threshold of 150mg/L on postoperative days (POD) 3 and 4 was used to identify outliers by funnel plot analysis. Surgeons with significant differences in the proportion of patients exceeding POD 3 CRP 150mg/L were compared. Significantly different perioperative variables amongst surgeons, and the surgeons themselves, were then entered into a multivariate binary logistic regression model to asses association with POD 3 CRP. Results: Perioperative factors were compared between 3 surgeons with the highest volumes and greatest difference in the proportion of patients exceeding POD 3 CRP 150mg/L (Figure 1); (35% of 137, 50% of 117, 60% of 92, p < 0.001). Amongst the 3 surgeons there were significant differences in comorbid state (p = 0.042), the proportion of patients undergoing minimally invasive surgery (p < 0.001), or surgery lasting over 4 hours (p < 0.001), requiring blood transfusion (p = 0.038), epidural anaesthesia (p < 0.001), and receiving perioperative steroids (p < 0.001). When those factors which were significantly different between surgeons were entered into a multivariate binary logistic regression model to predict exceeding the POD 3 CRP threshold of 150mg/L, only perioperative dexamethasone (OR 0.40, 95% CI 0.19-0.82, p = 0.012), and postoperative complications (OR 2.22, 95% CI 1.14-4.32, p = 0.018), remained independently associated whilst the surgeons themselves were not significantly associated (OR 1.16, 95% CI 0.59-2.30, p = 0.663). Conclusions: This study suggests that surgeon specific difference in the magnitude of the postoperative systemic inflammatory response are related to differences in surgical approach, anaesthetic technique and complications.