Recently there has been a strong demand to protect human skin against negative effects of the UV solar light. This problem is interesting due to the increased frequency of human diseases caused by such radiation. We aim to evaluate how the optical properties of the horny layer of skin can be effectively changed by imbedding fine particles to achieve the maximal attenuation of the UV solar radiation. In-depth distribution of particles embedded into the skin by multiple administration of sunscreens is determined experimentally using the tape-stripping technique. A computer code implementing the Monte Carlo method is developed to simulate photon migration within the -thick horny layer filled with nanosized spheres, in diameter. Dependencies of the UV radiation of two wavelengths (310 and ) absorbed by and totally reflected from, as well as transmitted through the horny layer on the size of particles are obtained and analyzed. The most attenuating particles are found to be 62 and in diameter for 310- and light, respectively. The former could be suggested as the main fraction to be used in sunscreens to prevent erythema.