BACKGROUND The optimal time point for surgical management of advanced parapneumonic empyema in need of open pleurectomy and decortication remains unclear. We hypothesized that surgical outcomes will be better when procalcitonin (PCT) levels have dropped to normal ranges as evidence for resolution of the underlying pneumonia. METHODS We retrospectively analyzed outcomes of 38 patients with advanced parapneumonic empyema who underwent open decortication and pleurectomy with available preoperative PCT (pPCT) values. Patients were divided into two groups based on the pPCT cut-off of 0.25 µg/L. Total length of stay was the primary endpoint. Secondary endpoints included postoperative length of stay, surgery-related complications and death. RESULTS Patients with a pPCT ≥0.25 µg/L had a significantly longer total length of stay compared to patients with a pPCT level <0.25 µg/L [mean 22.4 vs. 15.0 days, difference -7.4 days (95% CI: -12.8 to -2.0), P=0.009]. This was also confirmed in linear regression analysis adjusting for age, gender and comorbidities [adjusted regression coefficient for log-transformed length of stay -0.27, 95% CI: -0.02 to -0.52, P=0.037]. Results for postoperative length of stay were similar. Eight patients in the pPCT ≥0.25 µg/L group had postoperative complications with two deaths while no complications occurred in the PCT <0.25 µg/L group (38% vs. 0%, P=0.004). CONCLUSIONS These data suggest better surgical outcomes in advanced parapneumonic empyema when pneumonia has resolved with a pPCT drop of <0.25 µg/L. A larger, prospective study is needed to confirm these results.