Evaluation of: Riedel S, Melendez JH, An AT, Rosenbaum JE, Zenilman JM. Procalcitonin as a marker for the detection of bacteremia and sepsis in the emergency department. Am. J. Clin. Pathol. 135(2), 182-189 (2011). In a recent report, Riedel et al. proposed a procalcitonin cutoff of 0.1 ng/ml to rule out bacteremia in adult patients presenting to the emergency department with systemic infections. Procalcitonin levels were higher in patients with true bacteremia than in patients with negative blood cultures or bacteremia due to possible contaminants. For prediction of bacteremia, a procalcitonin level of 0.1 ng/ml had an excellent negative predictive value of 96.3%, and a good sensitivity of 75%, specificity of 70.6% and area under the curve of 0.73, but poor positive predictive value of 12.8%. Based on the results in this study, we propose that a procalcitonin value of 0.1 ng/ml or less could be used to rule out bacteremia (NPV: 96.3%).