Textiles can provide effective protection against UV radiation because they reflect, absorb and scatter solar wavelengths. Properly designed, they significantly increase the area of covered skin. The optimal combination of thickness, fabric density, mass per unit area, knitted structure, yarn type and yarn linear density, facilitate the production of textiles with high UV protection properties. The objective of this research was to evaluate the impact of elastane on UV protection properties of viscose and polyacrylonitrile knitted structures. The investigation illustrated that wet relaxed elasticized knits show good UV radiation protection with UPF 20-40. In contrast, non-elasticized viscose and polyacrylonitrile knits are inappropriate for UV radiation protection. Comparing viscose samples, UPF is higher for dry relaxed elasticized structures, whilst for polyacrylonitrile samples, UPF is higher for wet relaxed elasticized structures. For non-elasticized structures, the UPF of polyacrylonitrile samples is greater than that of viscose samples. Generally, polyacrylonitrile knits investigated ensure better UV protection than viscose knits.