Background: Biomarker combinations can improve timely diagnosis and survival. Objective: To determine the usefulness of serum procalcitonin concentration (PCT), C-reactive protein (PCR) and the PCR/PCT index as predictors of mortality.Method: Retrospective study of patients diagnosed with abdominal sepsis during the period from April 2017 to February 2018. Results: We included 182 cases. In the survivors, the mean PCR was 170 and procalcitonin (PCT) 10.5. In the deceased, the mean of C-reactive protein (CRP) was 328 and that of PCT was 17.6. When applying the student's t-test for independent samples, it was found that these differences were significant for PCR (p = 0.001); however, for PCT it was not significant (p = 0.460). Afterwards, the PCR/PCT index was studied, as a predictor of mortality, in the deceased cases a PCR/PCT score of 7534 (standard deviation [SD]: 19,303) and for survivors of 538 (SD:805) (p = 0.001) was obtained. Conclusion: CRP is associated with mortality, serum PCT does not correlate with mortality. The PCR/PCT index seems to be a better indicator to predict mortality in patients with abdominal sepsis due to secondary peritonitis.