A systematic study on the rheological properties helps to identify suitable processing and compositional windows for foaming polylactic Acid (PLA)/poly epsilon-Caprolactone)(PCL) blends. In this article, the correlation between the rheological behavior, the blend morphology, as well as the resultant cellular structure of microcellular injection molded PLA/PCL blends was investigated. The addition of PCL had a significant effect on the storage modulus of PLA melts. With increasing the PCL content (less than 30%), the storage modulus increased due to the entanglement of polymer chains. The enhancement on their complex viscosities led to a better foaming behavior and pore microstructure. Porous structures with enhanced pore uniformity, decreased cell size, and higher cell density were observed in the PLA/PCL (70: 30) specimens. (C) 2016 Society of Plastics Engineers