Objective: To investigate the feasibility of grayscale ultrasound and quantitative shear wave elastography (SWE) for assessing the image features and stiffness of the Achilles tendon in patients with familial hypercholesterolemia (FH) compared with healthy controls. Methods: A total of 38 Achilles tendons from healthy control participants and 94 from patients with FH were examined with grayscale ultrasound and SWE. Each Achilles tendon examination was performed on 3 different segments (proximal, middle, and distal). The thickness, grayscale image features and elasticity modulus of each segment was measured on longitudinal views. Results: In Achilles tendons of healthy control participants, the thicknesses of the proximal, middle, and distal segments were (4.46 +/- 0.68) mm, (5.41 +/- 1.01) mm, and (4.41 +/- 0.57) mm, respectively. The grayscale features were diffusely hypoechoic with parallel linear hyperechoic striations. The mean elasticity modulus of the proximal, middle, and distal sites was (418.08 +/- 43.13) kPa, (425.78 +/- 47.14) kPa, and (407.79 +/- 38.74) kPa, respectively. In the FH group, the thicknesses of the proximal, middle, and distal segments were (7.65 +/- 3.09) mm, (11.46 +/- 4.84) mm, and (8.14 +/- 2.90) mm, respectively. The grayscale features were hypoechoic with linear hyperechoic disordered fibre distribution (92/94). Two of 94 Achilles tendons had considerable focal hypoechogenicity. Seventeen of 94 Achilles tendons had calcifications. In the FH group, the mean elasticity modulus of the proximal, middle, and distal segments were (294.86 +/- 58.13) kPa, (280.93 +/- 63.58) kPa, and (282.41 +/- 56.47) kPa, respectively. Statistically significant differences were found between the Achilles tendons of healthy control participants and FH patients in the thicknesses and mean elasticity modulus at the proximal, middle and distal segments of the Achilles tendons (all P < 0.001). Conclusions: Our results suggest that the grayscale features and SWE characteristics of the Achilles tendon provided complementary biomechanical information for quantitative assessment the Achilles tendon in patients with FH.