Tamoxifen citrate, a non-steroidal anti-oestrogen has potential applications in treatment of breast cancer. Biodegradable microspheres of PLGA 65: 35 were prepared by o/w emulsification solvent evaporation method. In this study, different batches of varying concentration of drug, polymer, polyvinyl alcohol and solvent were prepared. All the batches prepared were characterized by particle size distribution, encapsulation efficiency and in vitro release behaviour. Drug, polymer and PVA concentrations were varied to obtain optimum release profile for sustaining the action of drug.