AimThis study aimed to assess the influence of the C-reactive protein (CRP) level on the early outcome after elective colorectal resection. MethodPatients with colorectal cancer operated on between 2006 and 2013 were identified retrospectively. They were divided into a study group operated on between 2010 and 2013 when CRP was measured routinely on the fourth postoperative day and a control group operated on between 2006 and 2009 when the CRP level was not measured routinely. Mortality, intra-abdominal septic complications (IASC), abscesses and anastomotic leakage (AL), the need for reoperation, the interval from index surgery to relaparotomy, length of hospital stay and imaging studies were compared by multivariate analysis. ResultsA total of 1189 patients were assessed, including 598 (50.3%) in the study group (mean age 61.313years; 282 female) and 591 (49.7%) in the control group (mean age 61.8 +/- 11years; 267 female). There were seven (1.2%) postoperative deaths in the study group and nine (1.5%) in the control group (P=0.598). Abdominal ultrasound (US) was performed more often in the study group [97 (16.2%) vs 71 (12.0%); P=0.037]. In the study group the interval to diagnosis of IASC was shorter than in the control group (5.7 +/- 1.5days vs 7.3 +/- 1.3days; P=0.029). The decision to reoperate was also made earlier in the study group (6.2 +/- 1.7days vs 7.4 +/- 2.8days; P=0.043). ConclusionRoutine measurement of CRP can help to make an earlier diagnosis of IASC and earlier decision for relaparotomy, without any influence on mortality or length of hospital stay.