STUDY OBJECTIVE To study the development and implementation of a hospital-wide protocol regarding preoperative beta-blocker therapy. DESIGN Prospective, observational clinical study. SETTING Preoperative test center at a university hospital. PATIENTS 1,000 consecutive patients presenting for a preoperative visit and scheduled for same-day admit surgery. INTERVENTIONS An algorithm of indications and contraindications for beta-blocker therapy was designed. Data were collected prospectively on 1,000 consecutive patients between June 1, 2004 and August 31, 2004. MEASUREMENTS Data collected included patient demographics, medication history, risk factors, indications and contraindications to beta-blocker therapy, as well as surgical risk stratification and postoperative complications. MAIN RESULTS 960 of the 1,000 patients underwent surgery and had complete information for the study collected. 169 patients (17.6%) were receiving beta blockers prior to evaluation. Of the patients having high-risk surgery, 72% had a major or minor indication for beta-blocker therapy without contraindication. Of the patients having intermediate or low-risk surgery, 10% had a major indication for beta blockers without contraindication. Overall, 52% (409/791) of the patients who were candidates for perioperative beta blockers were not receiving them. Some type of complication was experienced by 59 (6.1%) patients. CONCLUSIONS Development, implementation, and monitoring of perioperative beta-blocker therapy protocols is necessary, as a significant number of appropriate patients do not receive this therapy.