A biologically motivated mathematical model of the dynamics of swine skin epidermis after single acute irradiation () is extended to describe the effects of fractionated irradiation on this vital body system. The extended model, as the initial one, is a system of nonlinear ordinary differential equations whose variables and parameters have clear biological meaning. The performed studies of the model reveal a correlation between the dynamics of the dimensionless concentration of corneal cells of the upper skin layer and the dynamics of the fraction of the area of swine skin epidermis without moist desquamation under fractionated irradiation similar to that after single acute irradiation (). On the basis of these results, the formula, which allows computation of the dynamics of the moist desquamation in irradiated skin proceeding from the respective dynamics of skin epidermal cells, is proposed. It is demonstrated that the modeling predictions of the moist reaction in swine skin under fractionated irradiation in the wide range of total doses agree, on qualitative and quantitative levels, with the respective experimental data. All this bears witness to the validity of employment of the developed model, after appropriate identification, in the investigation and prediction of the effects of fractionated irradiation on skin epidermis in humans.