Objective: The objective of this prospective study was to compare the clinical value of procalcitonin (PCT) and C-reactive protein (CrP) plasma concentrations in their postoperative course after decortication. Methods: Twenty-two patients requiring surgery for pleural empyema were chosen for this prospective study. Routine blood samples including CrP and PCT plasma concentrations were taken before the operation and on the 1st, 2nd, 3rd, and 7th postoperative day. Results: Due to infection PCT and CrP were elevated preoperatively. In the postoperative course both PCT and CrP reached peak-levels on day 2 with values up to 43.55 ng/ml and 384.00 mg/l, respectively. In PCT the rise was followed by a clear decrease in 20 (90.9 %) patients until day 7. In contrast the CrP levels decreased slowly and only seven (54.5%) patients had values of 100 mg/l or below on day 7. PCT showed a better correlation with the clinic in case of septic course than CrP does. Conclusions: PCT reflects postoperative clinical course more accurately than CrP. Therefore, PCT is a more appropriate laboratory parameter to monitor patients after surgery for pleural empyema. #