To assess the significance of migration of polymeric plasticizers into foods, chemical characterization and quantification of individual oligomeric species is required. This paper reports the identification of seven individual oligomers isolated from a poly(butylene adipate) plasticizer. Based on mass spectrometry, NMR and chemical degradation, the oligomers were identified as a series of diol‐terminated units ranging from a trimer up to an 11‐monomer unit, along with a cyclic tetramer, all in the molecular weight range of 300–1100. A study of the migration of polymeric plasticizer from PVC film into olive oil indicated preferential migration of low molecular weight species. These oligomers which comprised 24% of the parent plasticizer contributed more than 90% of the plasticizer migration with the smallest oligomers migrating 90‐fold more readily than the bulk of the plasticizer. From a knowledge of total polymeric plasticizer migration from PVC films under actual conditions of food‐use, the abundance of individual oligomers in the foods has been estimated.