Background: Smoking is the main preventable cause worldwide of morbidity and premature death (1). It is a major and independent risk factor for coronary heart disease (CHD) (2). More than two-thirds of sudden cardiac death resulting from acute thrombus occurs in smokers (3). Compared to non-smokers the odds ratio (OR) for myocardial infarction is about 2.5, and for cardiovascular diseases overall the OR is about 2 (2) (4). Smoking cessation in persons with known CHD reduces the risk of recurrent myocardial infarctions or cardiovascular death by 30 % to 50 % (5,6) during the subsequent 3 to 7 years (7). Nevertheless, although smoking cessation is potentially the most effective CHD prevention strategy (5), quitting smoking is difficult and two-thirds of patients will return to smoking within one year of their acute coronary syndrome (ACS) (8,9). So, being hospitalized for a major cardiac condition, such as ACS can be an opportunity to prompt many individuals to stop smoking. Through using this "teachable moment" immediately after an ACS, it may be possible to increase smoking abstinence in this high-risk population (9). Cessation rates among smokers hospitalized for ACS, range from 31% without intervention to 60% with sustained intervention post hospitalization, at one year follow-up (10). Although Nicotine replacement therapy (NRT), Bupropion, and Varenicline have demonstrated efficacy medical treatment for smoking cessation compared with placebo (9). NRT improved cessation rates as well with an OR of 1.84 (95% CI 1.71 to 1.99) (2) and no adverse events was found (1). However, the smoking cessation remains a secondary concern in cardiology departments and there is no well strategies offered to these smoker patients with established CHD. Furthermore, there were no difference in cessation rates between this population and the general population despite the proved benefit of smoking cessation on clinical outcomes in CHD patients (11). Many studies have examined the benefits of smoking cessation after ACS and the efficacy of smoking cessation pharmacotherapy's in hospitalized patients with ACS but few randomized controlled trials have examined the efficacy time of smoking cessation in hospitalized patients with ACS either during the hospitalization or after hospital discharge. We aimed at comparing, among patients with ACS, the smoking cessation rates with NRT when began in-hospitalization, against that began after hospital discharge.