Quantitative ultrasound has been used to evaluate bone fracture healing for over five decades. Animal and clinical studies have showed that the propagation velocity and attenuation are significantly different between fresh fractures, bone unions, and delayed unions or non-unions. Follow-up measurements have also indicated that the velocity typically increases during healing which makes feasible to monitor the healing progress and early distinguish between normal healing and delayed unions. Researchers have recently used computer simulations aiming to gain insight into the underlying mechanisms of wave propagation in healing bones and interpret real measurements. In this chapter we present the state of the art in the field and provide an extensive review of the relevant literature.