In this study, biodegradable blends of poly(epsilon-carprolactone) (PCL) and poly(N-vinylpyrrolidone) (PVP) were prepared by a new strategy in the following steps: (1) free radical polymerization of N-vinyl-2-pyrrolidone (NVP) in epsilon-caprolactone (CL); (2) ring-opening polymerization of epsilon-caprolactone in the presence of PVP to obtain the target blends. The structure of the blends was confirmed by FTIR and H-l NMR, and the molecular weight of PCL and PVP were determined by GPS. SEM study revealed that this polymerization method could decrease the disperse phase size and improve the interphase when compared with solution-blending method. The phase inversion occurred when PVP content was 15-20 wt %. Subsequently, the PCL sphere dispersed in PVP matrix and its size decreased with the increase of PVP content. The contact angle results showed that PCL/PVP blend. PCL/PVP blends are believed to be promising for drug delivery, cell therapy, and other biomedical applications. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1676-1683, 2009