Elevated serum bilirubin concentrations protect from atherosclerotic diseases; however, it is not clear whether higher serum bilirubin concentrations in physiological ranges do the same. To investigate the association of high and low serum bilirubin concentrations with left ventricular diastolic function and aortic elastic properties. We evaluated left ventricular diastolic function and aortic elastic properties of 42 healthy subjects with hypobilirubinemia (total bilirubin 0.40 +/- 0.08 mg/dl; mean age 37.0 +/- 3.9) and 40 healthy subjects with hyperbilirubinemia (total bilirubin 1.56 +/- 0.49 mg/dl; mean age 36.2 +/- 6.0) using transthoracic second harmonic Doppler echocardiography. Age, gender, body mass index and coronary risk factors were similar between the groups, except high-sensitivity C-reactive protein (hsCRP). Left ventricular diastolic parameters were similar between the two groups. Aortic distensibility (AoD) was found to be significantly lower (11.1 +/- 3.9 vs. 13.2 +/- 4.9, p = 0.03) and aortic stiffness index (AoSI) (1.99 +/- 0.30 vs. 1.85 +/- 0.26, p = 0.02) and elastic modulus (AoEM) (2.06 +/- 0.83 vs. 1.73 +/- 0.68, p = 0.03; the low and high bilirubin groups, respectively) higher in the low bilirubin group. Serum total bilirubin concentration correlated with hsCRP levels, AoD, AoSI and AoEM. In conclusion, left ventricular systolic and diastolic functions were similar between hypo- and hyperbilirubinemic subjects, but aortic elastic properties were impaired in subjects with lower serum bilirubin concentrations.