his article reviews recent data on the usefulness of serum markers in community-acquired pneumonia and ventilator-associated pneumonia. The focus is on clinical studies, with an emphasis on adult critically ill patients. Recent findings Serum markers have demonstrated potential value in early prediction and diagnosis of pneumonia, in monitoring the clinical course and in guiding antibiotic therapy. C-reactive protein appears to perform better in diagnosing infection, because several studies have shown that procalcitonin may remain undetectable in some patients, specifically those with pneumonia. Procalcitonin exhibited a better correlation with clinical severity, however. Furthermore, one report demonstrated the efficacy and safety of procalcitonin-guided antibiotic therapy in community-acquired pneumonia. Summary Serum markers should only be used as a complementary tool to support the current clinical approach. Use of serum markers, in particular procalcitonin and C-reactive protein, represents a promising strategy in the clinical decision-making process in patients in whom pneumonia is suspected. Specifically, these markers can be used to guide culture sampling and empirical antibiotic prescription, and to monitor the clinical course, adjust the duration of antibiotic therapy and identify nonresponders, in whom an aggressive diagnostic and therapeutic approach may prevent further clinical deterioration.