Arterial stiffness is currently the "gold standard" measure of aortic (carotid-femoral) pulse wave velocity (PWV), which is an important independent predictor of risk of developing a cardiovascular event. Gilbert's syndrome is a congenital disorder characterized by intermittent and non-hemolytic elevation of indirect bilirubin levels due to the deficiency of the enzyme UDP-glucuronyl transferase in the liver and many prospective studies found an inverse relationship between bilirubin levels and cardiovascular events in these patients. We aimed to investigate serum bilirubin levels and arterial stiffness parameters in patients with Gilbert's syndrome in this study. A total of 53 cases, consisting of 26 patients with a diagnosis of Gilbert's syndrome and 27 healthy control subjects, were included in the study. Serum bilirubin levels, other routine blood chemistry, and arterial stiffness measurements were recorded. The mean ages of Gilbert's syndrome and the control group were 31.5 ± 9.7 and 36.8 ± 11.1 years, respectively. PWV measurements were significantly lower in Gilbert syndrome patients (6.68 and 7.3 m/s in patients and controls; respectively) (P < .05). In correlation analysis in Gilbert's syndrome patients, PWV had a significant correlation with total and indirect bilirubin levels (r = -0.370, P = .009/r = -0.495, P = .003, respectively). Gilbert's syndrome patients have lower PWV measurements compared to healthy subjects, and the total and indirect bilirubin levels are also associated with PWV measurements. These findings may indicate the decreased atherosclerotic disease incidence in Gilbert's syndrome patients.