A semi-interpenetrating polymer network (IPN) comprising gelatin and poly(2-hydroxyethyl methacrylate-co-acrylamide) was prepared and characterized by FTIR, environmental scanning electron microscopy (ESEM) and differential scanning calorimetry (DSC) techniques. The water sorption potential of the prepared semi-IPNs was investigated for varying chemical architecture of the IPN, and experimental conditions such as pH, temperature and ionic strength of the swelling media. The semi-IPNs were also judged for in vitro blood compatibility by performing blood clot, percent hemolysis, protein adsorption and platelet adhesion tests. (c) 2007 Wiley Periodicals, Inc.