Indiscriminant freezing doses not destroy tissue. The survival of frozen tissue depends on the thermal conditions during freezing. To control tissue destruction during cryosurgery it is important to understand the effect of thermal history on cell damage, and the mechanism of heat and mass transfer that lead to cell death. The aim of this work is to characterize the dependence of freezing damage on thermal parameters, by examining the heat and mass transfer processes which occur during freezing of prostate cells. This is done through two new experimental devices and methods for studying the effects of cellular dehydration and intracellular ice formation on cell viability. Based on empirical data produced with these new devices, analythical models have been developed to describe the modes of damage during cryosurgery. The analytical models are incorporated into a numerical simulation of prostate cryosurgery, to predict the outcome of a cryosurgical protocol from fundamental principles.