Thoracic aortic dissection (TAD) is estimated to occur at a rate of 3-4 cases per 100.000 persons per year and is associated with significant morbidity and mortality [1]. Recognized risk factors related to the occurrence of TAD are aortic dilatation, genetic syndromes and conditions with increased wall stress (i.e. hypertension, aortic coarctation or trauma injury)[2]. TAD presents with a tear in the innermost layer of the aorta and blood flows into the space between the inner and middle layers, causing the aortic wall to dissect [3]. During the cardiac cycle, the lesion is subjected to mechanical stresses due to pulsatile arterial pressure and flow. Investigating the conditions under which dissection takes place is fundamental to define patient risk. Computational models are widely used to quantify the risk rupture of the aorta. [4]. In-depth knowledge of the mechanical characteristics of dissected tissues in this regard is important to accurately simulate pathological conditions. In this study, the mechanical properties of human aortic dissection tissue were quantified using uniaxial and biaxial tensile tests. The adventitial and media flaps of TAD were collected from 15 patients (8 male, 7 female, age: 71 ± 10.4 years) who underwent repair surgery. The testing was performed within 48 hours after tissue collection. Uniaxial tissue specimens were classified according to their position (anterior or posterior) and their direction (circumferential or longitudinal). Biaxial tissue specimens were extract from the anterior aortic part. Stress-strain curve of experimental tests were analyzed to determine the mechanical properties of both adventitial and media flaps. Although men and women present a difference in average age not statistically significant, women prove to have a more stiff tissue, with a stress value to rupture higher than men at a comparable strain value. Regarding the position of the sample, comparing patients that present both specimens in anterior and posterior position, the posterior specimens appear to be more stiff compare to anterior ones. Finally experimental data shows how adventitial specimens, despite their very small thickness, present a very high deformation to rupture compared to media samples.