OBJECTIVES: To evaluate degree of implementation of the American and European guidelines related to the treatment as secondary prevention, in the management of patients with acute myocardial infarction with ST segment elevation (STEMI). METHODS: Cross-sectional and multicentric study realized in cardiology outpatient clinics in Spain. Physicians included consecutively outpatients over 18 years with STEMI happened within 2 previous years. The guidelines of reference were the American College of Cardiology / American Heart Association (ACC/AHA 2004) and European Society of Cardiology (ESC 2003). Descriptive statistics and comparison of averages ("t" of Student and Or of Mann-Whitney) and proportions (Chi-squared) were realized with SAS package. RESULTS: A total of 1439 out of 1588 patients were valid for analysis (90.6%). A total of 80.3% were males, middle age were 62.4 years-old (STD=11.8) and the average BMI was of 27.8 Kg/m2 (STD=3.7). The most frequent concomitant diseases were hypertension (53.6%) and diabetes mellitus type II (28.5%). The average of time after STEMI was 9.6 months (STD=7.2). The treatments more frequently used were statins (93.6%), aspirin (93.2%) and beta-blockers (83.5%). The treatments used in accordance with guidelines were antiaggregants/anticoagulants (99.7% in both guidelines), statins (94.4% in ACC/AHA and 93.5% in ESC) and beta-blockers (83.5% in both guidelines), staying in the second term ACE inhibitors/ARBs (78.2% ACC/AHA and 59.7% ESC) and aldosterone antagonists (19.3%), this one only recommended by the ACC/AHA. To summarize, 65.3% (ACC/AHA) and 52.4% (ESC) of the patients were being treated according guidelines. Regarding lifestyle factors, only 9.2% (ACC/AHA) and 6.4% of patients followed the overall guidelines' recommendations. CONCLUSION: This study shows a low implementation of guidelines by Spanish physicians in managing patients with STEMI, with more adherence to ACC/AHA 2004 than ESC 2003 guidelines. Treatment recommendations are more followed than life-style recommendations. Based on this study, actions are needed to increase adherence of Guidelines in Spain.