Objective: Gilbert's syndrome (GS) decreases the incidence of atherosclerotic heart disease. The aim of the study was to evaluate whether the arrhythmia risk markers such as P-wave dispersion (Pd), QT dispersion (QTd) are reduced in patients with GS compared with healthy subjects. Methods: Sixty-one patients diagnosed with GS (31 females, 30 males) who had applied to the internal medicine outpatient clinic in the hospital were included in this cross-sectional, observational study. A control group of 61 healthy persons (31 females, 30 males), who were non-smokers and drinkers, were included. Both groups were between 16-45 years old. Results of anthropometric measurements, laboratory assays and electrocardiographic findings were recorded for each participant. Independent sample t-test and nested ANOVA were used for data analysis. Results: In the GS group were Pd value 36±16.7 msec, QTd 48.7±10.7 msec and heart rate (HR) 74±8 beat/min. In the control group were Pd 51±28 msec, QTd 53±12 msec and HR 78±10 beat/min. The Pd of patients group (p<0.001), QTd (p=0.038) and HR (p=0.021) were significantly lower than the control group. Conclusion: According to our study's results, in these patients, increased bilirubin levels are associated with decrease in HR, Pd and QTd, which consequently might decrease the incidence of cardiac arrhythmias and coronary artery disease. Further studies are needed to clarify the protective role of bilirubin in risk of arrhythmias in this category of patients. (