Abstract: A plasticizer composition for synthetic resins, particularly polyvinyl chloride consisting essentially of (a) the phthalate ester of an aliphatic alcohol containing from 5 to 12 carbon atoms in the aliphatic moiety, e.g. diheptanyl or dialphanyl phthalate, and, intimately mixed therewith, a polyurethane resin which is the reaction product of a di-isocyanate and a polyester based in part on terephthalic acid, e.g. an hydroxy terminated polyester containing terephthalic acid, adipic acid, and hexane diol residues, which is particularly suitable for producing plasticized resins with low electrical conductivity.