A field experiment was carried out to evaluate the effectiveness of synthetic and natural preparations in protecting potato against Leptinotarsa decemlineata (Colorado Potato Beetle). Seven substances and microorganisms with proved or potential toxic effect on the pest were used: Neem extract (Azadirachta indica), suspensions of Beauveria bassiana Balsamo (Vuillemin) (Hypocreales: Cordycipitaceae) and Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) entomopathogenic fungal spores, natural pyrethrin and three chemical insecticides (lambda-cyhalothrin, thiamethoxam and imidacloprid). Plots where no protection measures were applied served as control. Chemical insecticides were more effective in controlling L. decemlineata larvae than natural preparations. It was found that chemical insecticides protected potato yield more effectively than the preparations containing natural pyrethrin or spores of entomopathogenic fungi. Tuber yield from the plots protected with entomopathogenic fungi and Neem extract was significantly higher than that on unprotected plots but still lower than the yield obtained from the plots protected with a chemical preparation.