Bone diagnosis using x-ray techniques, such as computed tomography and dual-energy x-ray absorptiometry, can evaluate bone mineral density (BMD) and microstructure but does not provide elastic properties. This study investigated the ultrasonic properties of racehorse leg cortical bone, focusing on the relationship between wave velocity, BMD, and hydroxyapatite (HAp) crystallite alignment. The results showed a strong correlation between wave velocity and BMD, suggesting that quantitative ultrasound-obtained wave velocity is primarily influenced by BMD, followed by the HAp alignment direction.