An insecticidal protein gene, vip3A, was cloned from Bacillus thuringiensis strain WB50. The nucleotide sequence of 2,460 bp (GenBank acc. No. AY295778) showed 99% homology with the known vip3A genes. Using specific primers for vip3A gene, PCR was performed to demonstrate that the gene was not located on the bacterial chromosome and this was confirmed by Southern blotting using an internal fragment (486 bp) from vip3A gene as a probe. The gene was carried on a plasmid of 31.8 kb.