Group II phospholipase A2 (PLA2-II), procalcitonin (PCT) and C-reactive protein (CRP) are useful indicators of the severity of inflammation in various infections. To compare their discriminatory abilities at an early phase of bacteremia, PLA2-II, PCT and CRP were measured upon admission and 24-48 h thereafter in 29 patients with bacteremia, non-bacteremic bacterial or viral infections. The levels of PLA2-II and PCT were higher in bacteremia than in non-bacteremic bacterial or viral infections. PCT was highest upon admission, PLA2-II peaked at 12-24h, whereas CRP peaked one day later. At < or =24h, the AUC(ROC)s of PLA2-II and PCT were superior to those of CRP. Thereafter, the AUC(ROC)s of PLA2-II and PCT decreased and those of CRP increased. PLA2-II at cut-off level of 150 microg/L and PCT at 2-6 microg/L showed high sensitivity and specificity for bacteremia within the first 24h. In conclusion, PLA2-II and PCT are useful markers for early diagnosis of bacteremia. Devising analytical methods suitable for point-of-care testing would further enhance the clinical utility of the measurement of serum PLA2-II and PCT.