Enzymatic degradation and polymerization using an enzyme were analyzed with respect to the establishment of a sustainable chemical recycling system for poly(epsilon-caprolactone) (PCL) which is a typical biodegradable synthetic plastic. As the typical example, the enzymatic degradation of PLC having an (M) over bar(n) of 110 000 using lipase CA in toluene containing water at 70 degrees C for 6 h afforded a unimodal oligomer having an (M) over bar(n) of about 1000 quantitatively consisting of liner and cyclic oligomers. This was again polymerized by lipase CA in toluene under restricted water concentration to produce PCL having an (M) over bar(n) of greater than 70 000.