Acetylcholinesterase (AChE) was purified from adult heads of a Korean housefly, Musca domestica, strain (KNIH) by affinity chromatography on trimethyl (m-aminophenyl) ammonium chloride resin. The purified AChE showed the purification factor over 400-fold and the specific activity of about $290mu extrm{mol}$/min/mg. The housefly has both the membrane-bound and the soluble forms of AChE. Only the membrane-bound form of the housefly AChE was isolated by Triton X-114 phase partition and revealed on the native gel. The maximum activities of the purified AChE were shown at pH 7.5-8.5 and 40-$45^{circ}$. Partial cDNA of AChE (795bp) of the KNIH strain showed that its deduced amino acid sequence shared high similarity with that of insecticide-resistant type of insect AChE.