Background: Psychological problems like as anxiety in patients who are candidate for coronary artery bypass graft (CABGs) may increase mortality and morbidity. The effect of reassurance and PREOPERATIVE INFORMATION in decreasing of anxiety is uncertain. This study designed to address the effect of PREOPERATIVE INFORMATION and reassurance in decreasing of anxiety of patients who are candidate for CABGs.Methods: With experimental study and randomize sampling 85 (55male and 30 female) of 238patients who were candidate for CABGs included and completed spilberger anxiety test on the day of admission. PREOPERATIVE in formation and reassurance done and test completed again on the day before surgery.Results: Mean number of anxiety score in patients with mild anxiety disorder (21 patients) were 34±4.2 before and 39±5.8 after intervention. In patients with moderate anxiety disorder (39 patients) the number decreased from 52.61±3.8 to 50.76±56. Twenty five patients had severe anxiety disorder before with number of 63.88±2.8 which decreased to 53.88±7.6. All of differences were significant statistically. Conclusion: In patients with mild anxiety PREOPERATIVE INFORMATION and reassurance resulted in increasing of anxiety but in patients with moderate or severe anxiety disorder, anxiety level decreased significantly.