To determine the impact of an educational program designed to modify test ordering behavior in an academic Emergency Department (ED), an observational, before-and-after study was conducted at a university tertiary referral center and Emergency Medicine (EM) residency site. Test ordering standards were developed by EM faculty, RNs, and NPs based upon group consensus and published data. The standards were given to all ED staff beginning February 1996, and included in the evidence-based medicine orientation and educational program for all residents and medical students prior to beginning their rotation. No restrictions were placed on actual test ordering. The number of laboratory tests (total and individual) ordered per 100 patients decreased significantly after the educational program began for: total testing, CBC, and liver function test (LFT). In addition, declines during individual months for these tests were statistically significant. Prothrombin time and blood culture testing showed no significant decreases in test ordering frequency. Chemistry test ordering frequency showed statistically significant increases. Overall, approximately $50,000 was saved by decreasing test ordering. Test ordering behavior can be modified and maintained by an educational program and may have significant economic effects.