In this article, transesterification of poly(bisphenol A carbonate) (PC) with a ethylene terephthalate-caprolactone copolyester at a weight ratio 50/50 (TCL50) was investigated by infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy (H-1-NMR), and a model compound. The IR and H-1-NMR results showed that transesterification occurred between PC and ethylene terephthalate (ET) segments in TCL50 and resulted in the formation of bisphenol A-terephthalate ester units as in the annealed blend of PC with the PET homopolyester. By comparison with a model compound, the new signal at 2.55 ppm in the H-1-NMR spectrum confirmed the appearance of bisphenol A-caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. The H-1-NMR analysis of the transesterification rates revealed that the reactions of PC with aromatic and aliphatic segments in TCL50 proceeded in a random or free manner. In addition, we separately examined the interchange reaction between a PC and poly(epsilon -caprolactone) (PCL) homopolyester in an annealed blend. It was found that in the presence of a Ti compound catalyst the predominant reaction was a transesterification rather than a thermooxidative branching reaction.