Background: Measuring arterial stiffness (augmentation index (AI), aortic pulse wave velocity (PWV)) in hemodialysis (HD) patients has prognostic significance. To assess its validity, the new oscillometric Arteriograph device (AI_A, PWV_A) was compared to the validated PulsePen tonometer (AI_P, PWV_P). Methods: AI and PWV were measured in 98 patients with both devices before HD. Validity was evaluated by Pearson’s correlation, Bland-Altman analysis, and by assessing the prognostic value of AI and PWV to predict cardiovascular (CV) mortality over 29 months. Results: Correlation between AI_P and AI_A was significant (R = 0.527, p < 0.001). The mean difference of AI values obtained by the two devices was –20.6%, and 30% of the paired AI differences fall outside the ±1 SD boundary of the mean between-device difference. There was no significant correlation between the PWV_P and PWV_A readings (R = 0.173, p = 0.097). The average difference of PWV values by the two devices was –1.2 m/s, and 20.6% of the paired PWV differences fall outside the ±1 SD boundary. In survival analyses, only PWV_P but not PWV_A was significantly related to CV mortality. Conclusion: Lack of correlation between PWV_P and PWV_A and lack of prognostic significance of PWV_A suggest limited validity of Arteriograph to determine PWV in patients on HD.