The enzymatic depolymerization of chitin has been explored in consideration of the disadvantages of the chemical hydrolysis, namely partial deacetylation of the resulting oligomers, difficulty of controlling depolymerization, low yield, cumbersome isolation of oligomer mixture, and heterogeneous conditions. Preparation of chito-oligomers by enzymatic depolymerization does not produce deacetylation. It would seem that the most obvious approach to the production of chitooligomers is the use of chitinases, but the comparative evaluation of the data obtained with other enzymes points to a different conclusion. In this chapter, the following depolymerization methods are presented and discussed: (1) chitinase on chitin, (2) chitosanase on chitin, (3) chitosanase on chitosan, (4) hemicellulase on chitosan, (5) lysozyme on chitosan, (6) papain on chitosan, and (7) lipase on chitosan.