Since the chromatographic separation of cholinesterase (ChE) by Malström in 1956 many investigator studied ChE isozyme, Harris divided five spots by two dimensional paper electrophoresis and starchgel electrophoresis, and referred as C1 C2 C3 C4. Clinically, Juul separated ChE 12 bands by polyacrylamidegel electrophoresis. We separated ChE as five bands using polyacrylamidegel electrophoresis, revealing fusion and deformity of the band. Takahashi et al reported separation of band using acetyl and butyrylthiocholine as substrate. They found abnormal band in liver cirrhosis, however they have thought it acetyl cholinesterase. Hada et al revealed a defect of band II in liver cirrhosis. They investigated ChE isozyme using affinity electrophoresis with Concanavalin A (Con A) and wheat germ agglutinin (WGA). They found disappearance of band 2, Con A and WGA containing agarose gel electrophoresis seem to be useful method in differentiating liver cirrhosis from chronic hepatitis. The number of isozyme fraction exhibited a species related variations in laboratory animals. Rats, hamsters guinea pigs, rabbits, dogs, monkeys, pigs, horses and quails have 4, 3, 4, 3-5, 3, 3, 4 and 3 isozyme bands, respectively.