Introduction: There is evidence that temporary defunctioning stoma formation in patients undergoing anterior resection reduces the risk of anastomotic leakage. The aim of the present study was to investigate the relationship between stoma formation, the postoperative systemic inflammatory response and complications following anterior resection for rectal cancer. Methods: Data was recorded prospectively for patients who underwent anterior resection for histologically proven rectal cancer, from 2008 to 2015 at a single centre, n = 167. Patients had routine preoperative and postoperative blood sampling including serum C-reactive protein (CRP). Postoperative complications including anastomotic leakage were recorded. Results: Of the 167 patients, the majority were male (61%) and over 65 years old (56%) with node negative disease (60%). 36 patients (22%) underwent preoperative neoadjuvant treatment. 100 patients (60%) had a stoma formed at the time of surgery. Stoma formation was significantly associated with male sex (69% vs. 50%, p = 0.017), neoadjuvant chemoradiotherapy (30% vs 9%, p = 0.001) and open surgery (71% vs. 55%, p = 0.040). Of those 100 patients who had a stoma formed, 80 had it reversed. Permanent stoma was significantly associated with increasing age (p = 0.011), exceeding the established CRP threshold of 150 mg/L on postoperative day 4 (67% vs 37%, p = 0.039), higher incidence of postoperative complications (76% vs 47%, p = 0.035), anastomotic leakage (24% vs 2%, p = 0.003) and higher Clavien Dindo score (p = 0.036). Conclusions: There was no significant association between stoma formation during anterior resection and the postoperative systemic inflammatory response. However, in these patients both the postoperative systemic inflammatory response and complications were associated with permanent stoma.