Delta-endotoxins from three new strains of Bacillus thuringiensis were purified using DEAE-Sephadex column chromatography. Proteolytic cleavage of the purified delta-endotoxins, using trypsin and chymotrypsin, gave different polypeptide patterns predicting differences in their aminoacids sequences. These differences were confirmed by a detailed immunological study, which revealed that the delta-endotoxins exhibit a degree of 30% to 40% homology.