Background Timely diagnosis and prognostic assessment of ventilator-associated pneumonia remain major challenges in critical care. Objective To explore the value of soluble triggering receptor expressed on myeloid cells 1, procalcitonin, and the Clinical Pulmonary Infection Score in the diagnosis and prognostic assessment of ventilator-associated pneumonia. Methods For 92 patients, bronchoalveolar lavage fluid was cultured for detection of microorganisms, serum levels of the receptor and procalcitonin and levels of the receptor in exhaled ventilator condensate were measured, and the Clinical Pulmonary Infection Score was calculated. Results On the day of diagnosis, patients who had pneumonia had higher serum levels of the receptor, procalcitonin, and C-reactive protein; higher white blood cell counts; and higher pulmonary infection and Sequential Organ Failure Assessment scores than did patients without pneumonia. White blood cell count (odds ratio, 1.118; 95% CI, 1.139-1.204) and serum levels of the receptor (odds ratio, 1.002; 95% CI, 1.000-1.005) may be risk factors for VAP. Serum levels of the receptor plus the pulmonary infection score were the most reliable for diagnosis; the area under the receiver operating characteristic curve was 0.972 (95% CI, 0.945-0.999), sensitivity was 0.875, and specificity was 0.95. For 28-day survival, procalcitonin level combined with pulmonary infection score was the most reliable for prognostic assessment (area under the curve, 0.848; 95% CI, 0.672-1.025). Conclusions In patients with ventilator-associated pneumonia, serum levels of the receptor plus the pulmonary infection score are useful for diagnosis, and procalcitonin levels plus the pulmonary infection score are useful for prognostic assessment. (American Journal of Critical Care. 2012;21:e110-e119)