native isolates of Bacillus thuringiensis were obtained from soil samples of various ecosystems in Mazandaran province and Cry1, the insecticidal protein-encoding gene, was detected in the isolates. About 491 bacilliform isolates were obtained from 128 soil samples through sodium acetate inhibition procedure. Two hundred ninety one spore-forming, 85 spore and cap-forming and 113 spore, cap and crystal forming bacteria representing 59.67, 17.31 and 23.01% 0f the isolated strains were identified by phase contrast microscopy. Molecular identification of Cry1 and its 14 related genes were carried out by 14 pairs of gene-specific primers. Fifteen isolates contained the Cry1 gene in the expected size. Cry1Ac and Cry1I were detected in all of the isolates but Cry1Aa, Cry1F, Cry1G and Cry1K were not entirely found. Cry1D, Cry1E and Cry1J were amplified in some of the isolates in different sizes: this could be attributed to the fact that they might have contained one or more new Cry genes. Detecting the effective genes of native Bt strains and their application in genetic engineering can be a useful component in future of insect pest management system.