During battlefield and mass casualty incidents, triage has been traditionally performed by many different personnel, including medics, nurses, dentists, and physicians. The objective of this study was to determine which military medical providers are most knowledgeable in mass casualty triage. The design was a prospective, written, timed, case-based examination of triage knowledge. Participants were volunteers from the active duty medical (physician), dental, nursing, and enlisted corps of the three military services. Subjects completed a 16-minute written examination consisting of seven cases in each of three simulated mass casualty scenarios: combat; nuclear, biological, and chemical; and humanitarian. Tests were taken anonymously, although demographic data on medical specialty, training, and experience were collected. Participants were instructed to classify the cases using the NATO categories of immediate, delayed, minimal, or expectant. Scores were tabulated according to two grading scales: an absolute scale of number correct, and a weighted scale amplifying gross misclassifications. Median scores between groups were tested pairwise using the Kruskal-Wallis one-way analysis of variance with p < or = 0.05. Statistically significant differences were noted between the highest and lowest scoring groups in each scenario. Our conclusion is that among the subject groups tested, physicians were best at mass casualty triage. Dentists, nurses, and medics scored progressively less well on our examination.