Background: Anomalous origin of coronary artery (AOCA) have been reported to be rare congenital anomaly and to be associated with myocardial infarction or sudden cardiac death, especially in the children and adolescents. However, a few of data about adults with AOCA have been reported up to date. Objective: The aim of this study is investigate clinical and angiographical characteristics of adults with AOCA. Methods: We evaluated the angiographic characteristics and clinical course of 95 AOCA patients with a mean age of 59.0짹11.5 years, identified by angiography or Multislice CT from Mar. 2000 to Jan. 2009 at our institute. A mean of clinical follow-up period after diagnosis of AOCA was 49.7짹35.8 months. Results: There were 76 cases (80.0%) of AOCA with RCA off the left coronary cusp (4 single coronaries, 4.2%), 3 cases (3.2%) with LCA off the right cusp, 8 cases (8.4%) with LAD off the RCA, 4 cases (4.2%) with LCX off the RCA, 1 case (1.1%) with LCA off the right subclavian artery, and 1 case (1.1%) with dual LCA os. Among 95 patients, 30 patients (31.6%: 29 patients; RCA off the LCC and 1 patient; LCA off the right subclavian artery) had a slit-like os. and 28 patients (29.6%) had concomittent coronary heart disease and/or valvular heart disease, and/or arrhythmia. 22 of 67 cases without concomittent disease had slit-like os. They presented resting symptoms more likely than cases without slit-like os. During the follow-up period, there was no death or myocardiac infarction among the cases without concomittent disease, 3 of whom underwent percutaneous coronary intervention, 2 patients as CABG, and 1 patient as reimplantation because of symptom aggravation or resting sypmtoms while 61 of 67 cases (91%) were treated medically (mainly beta-blocker and exercise restriction). Conclusion: RCA off the LCC showed highest incidence among adults with AOCA. Most of AOCAs seem to have benign course with only medical treatment in adults but some cases with slit-like os needed surgical or percutaneous intervention due to severe resting sypmptoms and/or symptoms aggravation.