In recent years, much research effort has been driven to develop alternative plasticizers for medical and commodity plastic materials. In this study, a modified natural plasticizer, synthesized by esterification of rice fatty acids, was modified by epoxidation with peroxy acid generated in situ. Two natural epoxidized plasticizers were obtained, using peracetic acid (NP-Ac) and peroctanoic acid (NP-Oc) as reagent. PVC films after addition of these natural epoxidized plasticizers presented fairly good incorporation and plasticizing performance, as demonstrated by results of mechanical properties, Tg values (as shown by DSC), optical microscopy, exudation, and migration tests, FTIR and X-ray diffraction obtained for plasticized PVC films. NP-Ac plasticizer presented enhanced plasticizing performance compared with NP-Oc, probably due to a higher epoxidation degree obtained in the reaction with peracetic acid. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013