Objective: Over one billion Muslims fast worldwide during the month of Ramadan. Fasting during Ramadan is essentially a radical change in lifestyle for the period of one lunar month, so it is important to see the response of congestive heart failure patients to this change. Our objective in this study is to investigate whether Ramadan fasting has any effect on the number of hospitalization for congestive heart failure (CHF) in a geographically defined population. Methods: We conducted a retrospective review of clinical data study on all Qatari patients in Qatar for a period of 10 years (January 1991 through December 2001) who were hospitalized with heart failure. Patients were divided according to the time of presentation in relation to the month of Ramadan, I month before, during and 1 month after Ramadan. The number of hospitalization for CHF 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. Results: Of the 20,856 patients treated during the 10-year period, 8446 of them were Qataris with 5095 males and 3351 females. Overall, 2160 Qatari patients were hospitalized for CHF and their mean age and standard deviation was 64.2 +/- 11.5 years, 52.4% were hypertensives, 18.5% had hypercholestrolemia, 17.7% were current smokers and 56.5% were diabetics. The overall mortality was 9.7%. The number of hospitalization for CHF was not significantly different in Ramadan (208 cases) when compared to a month before Ramadan (182 cases) and a month after Ramadan (198 cases); p > 0.37). There was no significant difference found in the baseline clinical characteristics or mortality (11.5%, 7.7% and 9.6%, respectively; p > 0.43) in patients presenting in various time periods. Conclusion: This population-based study demonstrates that no significant difference was found in number of hospitalization for CHF while fasting in Ramadan when compared to the non-fasting months. (C) 2003 Elsevier Ireland Ltd. All rights reserved.