OBJECTIVES: We aimed to investigate the value of leukocyte biomarkers and disease scores for the early detection of infection in patients who have undergone elective colorectal surgery for malignancy. METHODS: We conducted a prospective study at a training and research hospital. Patients who developed infection were considered to be an Infection group, and the others were regarded as a Control group. For individuals in both groups, the Sequential Organ Failure Assessment Score (SOFA), quick SOFA, and National Early Warning Score (NEWS) were calculated and blood samples were collected for flow cytometry analysis. A model was developed using logistic regression analysis to identify parameters that were predictive of mortality. RESULTS: One hundred thirty-two patients were included in the study. Infections developed in 36 (27.3%) of the participants, of which 14 (38.9%) were intra-abdominal, 10 (27.8%) were pneumonia, 8 (22.2%) were superficial incisional infections, and 4 (11.1%) were urinary tract infections. The NEWS was the most effective parameter for the detection of early infection in patients undergoing surgery for colorectal malignancy. CONCLUSION: The NEWS score can be easily used to predict infection soon after surgery for colorectal malignancy.