The purpose of this study was to compare the use of evidence based medicine in the guidelines published by the American College of Obstetrician and Gynecologists (ACOG) and Trauma Surgery (Eastern Association for Trauma Surgery [East]). We compared the references and the types of recommendations in ACOG and EAST guidelines. Odds ratio (OR), along with 95% confidence intervals (CI) were calculated and 95% CI not crossing the integer 1 were considered significant. Over eight years (1998-2005), ACOG published 58 guidelines and EAST, 23. Among the references cited, randomized clinical trials (RCT) were noted in 17% (714/4225) for ACOG versus 9% (165/1850) among trauma surgery guidelines (OR 2.07; 95% 1.74, 2.48). ACOG guidelines were also significantly more likely to have recommendations based on RCT (29%; 135/464) than EAST (10%, 24/242; OR 3.73, 95% CI 2.34, 5.94). East and ACOG guidelines have significantly fewer RCT and recommendations based on them than previously thought.