['The prognostic value of elevated serum levels of procalcitonin (PCT) in patients early after cardiac surgery on cardiopulmonary bypass (CPB) remains unclear. In a prospective study, we investigated whether PCT is useful as a prognostic marker in cardiac surgery with respect to mortality, complications and infections, and whether PCT is a specific marker for occurrence of infections.', 'Within 8 months, a subset of 80 high-risk patients (APACHE II-score: 25.1 +/- 4.7 (mean +/- SD)) out of a consecutive cohort of 776 patients was investigated. Demographic data, operative data and clinical endpoints (mortality, infection, severe complication) were documented. Serum levels of PCT were analyzed preoperatively and at postoperative day 1.', 'Hospital mortality in this high-risk group was 21.3 %, infections occurred in 33.8 % and complications in 58.8 % of the patients. Preoperative PCT was normal in all patients. Postoperative PCT was increased in non-survivors compared to survivors (34.3 +/- 7.0 ng/ml vs. 15.9 +/- 4.9 ng/ml; p < 0.05), in patients with severe complications (30.3 +/- 6.7 ng/ml vs. 5.5 +/- 1.4 ng/ml; p < 0.05) and in patients with infections (38.4 +/- 11.3 ng/ml vs. 10.8 +/- 1.6 ng/ml; p < 0.05). Area under receiver operating characteristic curve for PCT as predictor of mortality, infections and complications was 0.772 (95 %-confidence-interval (CI): 0.651 - 0.894), 0.720 (95 %-CI: 0.603 - 0.837) and 0.861 (95 %-CI: 0.779 - 0.943), respectively. PCT was not different with infectious compared to non-infectious complications.'] Is procalcitonin a valuable prognostic marker in cardiac surgery but not specific for infection?