Aqueous crystallization of polyester

A process of increasing crystallinity of water-insoluble crystallizable polyester pellets in an aqueous medium which comprises crystallizing polyester pellets having a diameter of 0.5 mm to 2.0 mm and 0.5 mm to 4 mm in length in an aqueous medium at about 50.degree.-150.degree. C. containing 0.0001 to 5% by weight of at least one surface active agent capable of preventing agglomeration of said polyester pellets selected from the group consisting of nonionic surface active agents and anionic surface active agents and dewatering said polyester pellets, wherein said polyester pellets comprise from 5-60% by weight of the aqueous bath.