The cadherinlike proteins, located in the brush border membrane vesicles (BBMV) of the insect midgut, are major receptors of Bacillus thuringiensis insecticidal crystal protein. The complete cDNA sequence of the cadherinlike protein gene in the beet armyworm, Spodoptera exigua (Hübner) was amplified using RTPCR and RACE techniques. The full cDNA sequence (named as SeCAD, GenBank accession no. HQ647122) is 5 582 bp in length, encoding 1 739 amino acid residues. The deduced amino acid sequence shows typical characteristics of the known insect cadherin proteins, including a signal peptide, a proprotein region, eleven cadherin repeats, a membraneproximal region, a transmembrane region and a cytoplasmic region. The predicted molecular weight and isoelectric point are 196.447 ku and 4.47, respectively. The cadherinlike protein from S. exigua shows a close relationship to cadherin proteins from Sesamia inferens, S. nonagrioides, Heliothis virescens and Helicoverpa assulta, with amino acid identity of 61.28%, 60.34%, 60.14% and 60.08%, respectively. These results can provide a basis for revealing the insecticidal mechanism of Bt in S. exigua, and the resistance mechanism of S. exigua to Bt.