A physical model to describe ultrasonic wave propagation in cancellous bone has been described in this thesis. The theoretical background for this model is based on Biot's theory. In order to prove the effectiveness and accuracy of this model, a broadband ultrasonic experimental system to study the ultrasonic properties of porous media was built as part of this project. The configuration details of this system as well as the fûndarnental techniques of measuring the attenuation and propagation velocities in a medium are presented in thîs thesis. The results of ultrasonic studies on water-saturated aluminum foams. which were used extensively as cancellous bone phantoms for studying basic mechanisms of wave propagation, and a detded theoretical analysis of these experimental results are also presented. The experiments agree very weli with the physical model established in this study. To extend this physical model to cancellous bone, several bovine bone samples and two types of cancellous bone phantoms were tested. The results of these experiments are also analyzed by the model.