We read with great interest the article by Rau et al1 in the February issue of the Archives. The authors have nicely shown that procalcitonin (PCT) monitoring is a fast and reliable approach to assess septic multiorgan dysfunction syndrome and prognosis in secondary peritonitis. We provide additional data suggesting that this conclusion has to be tempered in the early postoperative period in patients in the intensive care unit with septic shock related to secondary peritonitis. We prospectively studied 35 severely, critically ill patients with bacteriological proven secondary peritonitis (median Acute Physiology and Chronic Health Evaluation II score, 18 [interquartile range, 8]). Plasma levels of PCT were measured daily during the first 5 postoperative days. Simultaneously, sequential organ failure assessment scores were recorded. Consistent with the findings by Rau et al, PCT plasma levels were of no value for predicting intensive care unit mortality. However, we found that postoperative PCT levels failed to show any diagnosis value related to proven persisting intra-abdominal sepsis (area under the receiver operating characteristic [ROC] curve at day 3, 0.58 [confidence interval, 0.43-0.65]). Interestingly, sequential organ failure assessment scores exhibited a significant diagnosis (area under the ROC curve at day 3, 0.73 [confidence interval, 0.53-0.93]) and prognosis value (area under the ROC curve at day 5, 0.89 [confidence interval, 0.74-1]). While the accuracy of early postoperative PCT monitoring to recognize persistent abdominal infection in severely ill patients in the intensive care unit is questionable, we suggest that daily monitoring of sequential organ failure assessment scores may be of great diagnostic and prognostic interest in this patient subpopulation.