The ideal management of infection includes not only the early identification and start of effective therapy but also the correct categorization of non-infected patients in order to avoid unnecessary use of antimicrobials. The availability of a specific and sensitive test for the presence of infection is of paramount importance to improve the prudent use of antimicrobial therapy. Procalcitonin (PCT) has been evaluated over recent years as to whether it can be used to detect the presence of different types of infection, allows reduced duration of antibiotic therapy, or predicts treatment failure or adverse outcome. In the previous issue of Critical Care, Jung and colleagues report about the monitoring of treatment response in abdominal sepsis by repetitive determination of PCT.