The aim of this study was to validate whether differences in aortic stiffness are responsible for the differences in cardiovascular mortality among hypertension subtypes. Twenty hundred and fifty continuous ambulatory peritoneal dialysis patients were included in the present study. They were classified into four groups: normotensives (n=92) with systolic blood pressure (SBP) <140 mmHg and diastolic blood pressure (DBP) <90 mmHg; isolated systolic hypertensives (ISH, n=84) with SBP > or =140 mmHg and DBP <90 mmHg; isolated diastolic hypertensives (IDH, n=21) with SBP <140 mmHg and DBP > or =90 mmHg; and systolic-diastolic hypertensives (SDH, n=53) with SBP > or =140 mmHg and DBP > or =90 mmHg. Aortic stiffness was assessed by pulse pressure, central pressure parameters and pulse wave velocity. The IDH group had more male patients and a lower mean age than the other groups. The percentage of diabetes in the ISH group was higher than that in the other groups. The comparisons of aortic stiffness showed that the ISH and SDH groups had higher aortic stiffness than the normotension and IDH groups. The aortic stiffness in the ISH group was also higher than that in the SDH group, but there was no significant difference in aortic stiffness between the normotension and IDH groups. In conclusion, this study showed that aortic stiffness was significantly different among different hypertension subtypes, which might be an underlying cause of the differences in cardiovascular mortality among the hypertension subtypes.