Every day, critical care physicians around the world face the same challenge of the optimal timing of antimicrobial administration: when to start and when to stop antibiotics. Duration of antibiotic therapy for sepsis is mostly based on expert opinion, but its reduction is arguably the most promising approach to decrease emergence and selection of antibiotic resistance. The study by Hochreiter and colleagues presents another piece of evidence suggesting that procalcitonin may indeed be a valuable diagnostic parameter to guide antibiotic treatment duration, despite the ongoing controversy about the diagnostic accuracy of pro-calcitonin.