Augmentation index (AIx), derived from aortic pulse waveform, is related to arterial stiffness and increased cardiac workload. Sex differences were observed in the relationship between blood pressure (BP) and AIx at rest. In addition, positive correlation between BP and AIx in men during a pressor stimulus was observed previously. However, whether BP is important to acute changes of AIx also in women is yet to be investigated. Therefore, we sought to investigate whether there are sex differences on the relationship between BP and AIx. In all, 16 men (age 27 ± 5 yr; height 176 ± 1 cm; weight 77 ± 7 kg; mean ± SD) and 13 women (age 26 ± 5 yr; height 164 ± 0.3 cm; weight 63 ± 7 kg; mean ± SD) underwent 3 min of rest followed by 3 min of cold pressor test (CPT). Heart rate during CPT was similar to rest. CPT increased BP in both groups and the magnitude was similar between groups. AIx and left ventricle energy wasted (EW) increased (men Δ13 ± 5% and women Δ17 ± 3%; p > 0.05 for group; men Δ580 ± 242 dynes cm-2 s-1 and women Δ618 ± 123 dynes cm-2 s-1; p > 0.05 for group) similarly in men and women during CPT. A positive Pearson correlation was found between AIx and BP in men (systolic BP (SBP) r = 0.77, p = 0.01; diastolic BP (DBP) r = 0.79, p = 0.01 and mean arterial pressure (MAP) r = 0.83, p < 0.01), however no correlation was seen in women (SBP r = 0.04, p = 0.89; DBP r = 0.24, p = 0.44 and MAP r = 0.23, p = 0.44). The contribution of BP to acute changes in AIx at higher levels of BP is different between men and women.