During Ramadan, the ninth month of the Islamic lunar calendar, adult Muslims are required to refrain from taking any food, beverages, or oral drugs, as well as from sexual intercourse between dawn and sunset. In this study, we aimed at discovering alterations in drug regimens and the seizure frequency of epileptic patients during Ramadan (15 October 2004-13 November 2004). In the 3 months following Ramadan in the year 2004, 114 patients with epilepsy who were fasting during Ramadan were examined at our Epilepsy Department. Of the 114 patients who were included in the study, 38 patients had seizures and one of these patients developed status epilepticus during Ramadan. When the seizure frequency of these patients during Ramadan was compared to that in the last 1 year and last 3 months period just prior to Ramadan, a statistically significant increase was observed (p<0.001). Moreover, there was an important increase in the risk of having seizures in the patients who changed their drug regimens compared with those who did not (p<0.05). In the patients who received monotherapy or polytherapy, no difference in the frequency of seizures during Ramadan was seen (p>0.05). During Ramadan, an increase in the seizure frequency of patients with epilepsy was observed. The most important reason for this situation was the alteration in the pharmacokinetics and pharmacodynamics of drugs, and consequently, in their efficacy. We believe that in the patients who received monotherapy and who did not change their drug regimes, the increase in seizure frequency may have been related to the changes in their daily rhythms, emotional stress, tiredness and their day-long fasting.