Background:The SYNTAX score was developed as an angiographic tool to grade the complexity of coronary artery disease in patients with three-vessel and/or left main disease. The role of this score in predicting clinical outcomes after percutaneous coronary intervention (PCI) in non-selected patients treated in the daily clinical practice of a referral centre was evaluated. Methods: Analysis of patients undergoing PCI from March to September of 2009, and at the 12-month follow-up. Patients were divided into tertiles according to the SYNTAX score. The primary endpoint included major adverse cardiac events (MACE) -death, non-fatal acute myocardial infarction, and target-vessel revascularisation. The ability of the SYNTAX score to predict MACE was assessed by the receiver operator characteristic (ROC) curve. Results: Two hundred and thirty-four patients with a mean SYNTAX score of 11.6 ± 6.2 points were included. Tertile I had a SYNTAX score ≤ 9 (average 5.9); tertile II, > 9 and ≤ 13 (average 10.8); and tertile III, > 13 (average 18.3). During the clinical follow-up of 7.2 ± 4.9 months, the incidence of MACE was greater in tertile III than in tertiles I and II (2.5% vs. 6.4% vs. 14.1%; P = 0.0075). The ROC curve showed an area under the curve of 0.667 (P = 0.012), indicating a moderate ability to anticipate the occurrence of MACE in this population. Conclusions: The SYNTAX score proved to be useful in predicting the occurrence of MACE after PCI in patients treated in clinical practice.