We study variation of acoustic properties of samples of bone tissue in the process of their deorganification in the 5.25%-solution of sodium hypochlorite and in the course of their dehydration in the 100%-acetone. We use methods of acoustic microscopy. Based on the experimental data obtained, we calculate values of mechanical parameters of these samples. It is established that moderate variation in density of samples in the course of deorganification leads to profound decreasing in the sound velocity and more pronounced decreasing in the values of elasticity moduli. During the process of dehydration in acetone, density of the samples decreases by 5% (the averaged value) while the speed of ultra-sound wave decreases by 8-10% both in the longitudinal and transversal directions. As a result, we calculate an effective modulus of longitudinal wave and establish that its value increases by 15% (averaged value) in the course of dehydration.