A new gene, named Dd-ace-1, encoding an acetylcholinesterase (AChE , EC3.1.1.7) was cloned from the sweet potato stem nematode, Ditylenchus destructor. The full length cDNA, carrying the transspliced SL1 leader sequence, is 2196bp long with an open reading frame of 1908bp encoding 635 amino acid residues ( GenBank accession no. EF583059). The complete amino acid sequence of AChE deduced from the cDNA consists of 24 residues for the putative signal peptide and 611 residues for the mature protein with a predicted molecular weight of 70144.12D. The conserved motifs involved in the catalytic triad, the choline binding sit and 10 aromatic residues lining the catalytic gorge were present in the Dd-ACE-1 deduced protein. The predicted protein shared with strong homology with Meloidogyne incognita ACE-1, Dictyocaulus viviparous ACE-1 and Caenorhabditis elegans ACE-1. Phylogenetic analysis based on other nematodes and species AChEs showed that the deduced AChE formed a cluster with ACE-1s.