Bacillus thuringiensis strain WZ-9, isolated from soil in Hebei province, China, was effective against Henosepilachna vigintioctomaculata larvae. The strain presented bipyramidal crystals with a protein band of 130 kDa in SDS–PAGE. The pH changes of the culture media showed important fluctuations during the 24 h growth cycle. The pH varied less in log and stationary phases than it did in the exponential phase. Bioassay results showed that the WZ-9 strain was only harmful to larvae of H. vigintioctomaculata and not to either adults of H. vigintioctomaculata or other several lepidopteran and coleopteran insects. LC50 to second-instar larvae of H. vigintioctomaculata was 2.95×107 cells/ml after 72 h. Genotypic investigations showed that this strain possessed the cry7 gene. Sequence analysis demonstrated that the encoding gene contained an open reading frame (ORF) of 3414 bp and encoded 1138 amino acid residues. The deduced amino acid sequence was 99.65% identical to that of the reported Cry7Ab2 sequences. This gene was designated by the Bt δ-endotoxin nomenclature committee as Cry7Ab3 with accession number BI 1015188 in the GenBank database.