The miscibility and microstructure of blends of bisphenol-A polycarbonate (PC) with ethylene terephthalate (ET)-caprolactone (CL) copolyesters (TCL) were studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR) and phase contrast microscopy (PCM). The DSC results showed that PC were immiscible or partially miscible with the copolyesters having ethylene terephthatate contents higher than 60 (wt %), and miscible with the copolyesters having ET contents lower than 60 (wt %). After annealing at elevated temperature, homogenization will take place in the immiscible or partially miscible blends of PC with higher ET-content copolyesters. The IR and PCM results revealed that the homogenization of the blend are caused by the transesterification between the PC and copolyesters.