The presence of the B component of hemolysin BL (hblA), enterotoxin BceT (bceT), and enterotoxin S (entS) genes in mosquito-larvicidal Bacillus sp., including 25 B. sphaericus and 4 B. thuringiensis subsp. israelensis strains, has been analyzed by multiplex PCR in this study. The results showed that all four B. thuringiensis strains contain the hblA gene and the sequences of bceT and entS genes. However, none of the enterotoxin gene sequences were detected in the B. sphaericus strains. The enterotoxin production in all strains has also been analyzed by using two commercial immunoassay kits (TECRA and RPLA), and it has been proved that all the B. thuringiensis strains and one B. cereus strain can produce enterotoxins during growth. No enterotoxin activity could be detected in B. sphaericus strains.