An emulsion polymerisation method for the preparation of thermoresponsive hydrogel microspheres based onN -isopropylacrylamide is described in this paper. It was found that microsphere size distribution could be altered by varying the rate of stirring during the polymerisation process and also by modifying the concentration of lecithin. Microspheres were imaged in the fully hydrated state using environmental scanning electron microscopy (ESEM). Thermoresponsive release of a model drug from the microspheres was found to be a function of microsphere size, with improved control as microsphere size increased.