Porosity in structural materials limits their ultimate strength and hence their utility. Recently several studies which discuss the porosity induced ultrasonic attenuation have appeared [1–8]. Porosity assessment by ultrasonic attenuation measurement involves two principal problems: first, how to relate the porosity induced ultrasonic attenuation to porosity parameters such as average pore radius and volume fraction, and second, how to separate the sought porosity induced attenuation from other components contributing to the actually measured total attenuation.