Many of theworld's religions recommend periods of fasting and, of these; the Islamic fast during the month of Ramadan is strictly observed worldwide by millions of Muslims. Muslims neither eat nor drink anything from dawn till sunset, a period that varies with the geographical site and the season that in summermonths and northern latitudes, the fast can last up to 18 hours ormore [1]. Muslims observing the fast must not only abstain from eating and drinking, but also from taking oral medications as well as intravenous fluids and nutrients. In addition, there is associated altered sleep–wake schedule that causes an increase in daytime sleepiness, yet the demands of the daily routine (including religious considerations) reduce the chances that individuals will take a daytime nap to compensate [2]. Fasting during Ramadan is therefore a radical change in lifestyle for the period of one lunar month. The rationale behind the relation of Ramadan fasting and the development of atrial fibrillation (AF) stems from several observations. On one hand, sleep deprivation and eating disturbances have been previously linked to AF and pro-arrhythmia [3,4]. On the other hand favorable changes in lipid profile have been reported in relation to fasting during Ramadan [5] and this may at least in theory result in protection from myocardial ischemia, a known risk factor for AF. Therefore ourobjective in this study is to investigatewhether Ramadan fasting has any effect on the number of hospitalization with AF in the geographically defined population of Qatar. Qatar is a small Arab country with a population of around 600,000 (2001 Census) and 1.6 million (2010 Census), consisting of Qatari and otherMiddle-easternArabs (less than40%) aswell as other ethnic groups. This study focuses only onQatari patients rather than expatriates because it is a stable population and avoids the bias in thefluctuation of expatriate population in the country that varies from time to time. In addition, more than 95% of Qatari adults fast without fail during the month of Ramadan [6]. This study is based at Hamad General Hospital, Doha, Qatar. This hospital provides inpatient and outpatient medical and surgical care for the residents of Qatar; nationals and expatriates wheremore than 95% of cardiac patients are being treated in the country making an ideal center for population-based studies. The Cardiology and Cardiovascular Surgery Database at Hamad General Hospital was used for this study. Data were collected from the clinical records written by physicians at the time of patient's discharge from the hospital according to predefined criteria for each data point. These records have been coded and registered at the cardiology department since January 1991. With the described database, we conducted a retrospective review of clinical data study on all Qatari patients in Qatar for a period of 20 years (January 1991 through December 2010) who were hospitalized with AF [Table 1]. The study includedpatientswithfirst hospitalizations aswell as recurrences of AF. Patients were divided according to the time of presentation in relation to the month of Ramadan; 1 month before, during and 1 month after Ramadan. The number of hospitalization for AF in various time periods was analyzed. The age of presentation, gender, cardiovascular risk factor profiles (smoking status, hypertension, hypercholesterolemia, diabetes, pre-existing coronary heart disease) and outcome were analyzed [Table 2]. The ethics committee waived the need of informed consent because of its retrospective analysis and the fact that the data was analyzed anonymously. Of the 41,453 patients treated during the 20-year period, 1718 Qatari patients were hospitalized for AF [Table 1]. The number of hospitalization for AFwas not significantly different in Ramadan (143 cases) when compared to a month before Ramadan (136 cases) and a month after Ramadan (151 cases); [p = 0.95]. There was no significant difference found in the baseline clinical characteristics, presentation, in-hospital stroke or mortality in patients presenting in various time periods; p = non-significant for all except for patients with history of prior myocardial infarction (MI) were less likely to be hospitalized during Ramadan month (P = 0.01). The rate of hospitalizations of patients with underlying myocardial ischemia (as evidenced by concomitant acute coronary syndromes and/or history of oldMI) was significantly lower in Ramadan (9.8%) compared to other months (19.1% & 23.2%; P = 0.02) [Table 2]. The first finding of our study is that religious fasting has neutral overall effects on the hospitalizations rates with AF during Ramadan. Our findings are concordant with our previous work on Ramadan fasting and the burden of other cardiac disease [7–9], further