The present work stablished a bioassay methodology in order to determine B. thuringiensis Cry3Aa, Cry3Ba, Cry3Bb, Cry3Ca and Cry7 Aa standard proteins toxicity against Andean potato weevil (Premnotrypes vorax Hustache). This insect is a very important pest in almost all potato fields in Colombia. Bioassays were done using natural diet as potato tuber pieces or potatoe flour. Proteins were used as crystals, solubilized or enzimatically processed. Best bioassay used potato pieces superficially contaminated with the respective B. thuringiensis proteins. Although sorne toxicity were observed with Cry3Aa and Cry3Ca proteins, mortality never was over 10%. AH proteins were no toxic when tripsinated or solubilized at 4.1 pH. We concluded that Cry proteins eva1uated have no toxicity against P. vorax 1arvae. We hypothesized it could be due to its foreing origin, so further studies should involve evaluation of proteins produced by native strains isolated from potato fields where P. vorax is naturally present.