During the last two decades there has been a remarkable increase in interest in controlled release drug delivery system. Solid lipid nanoparticles (SLNs) of an anti migraine drug were produced with the solvent emulsification diffusion method using stearic acid as solid lipid, soya lecithin as phospholipid, poloxamer 188 as surface stabilizer and distilled water as dispersion medium. Three factors, two level factorial design was used for optimization of SLNs. Lipid concentration, lecithin concentration and stirring time were used as independent variables and entrapment efficiency and particle size as responses to get maximum entrapment efficiency along with lesser particle size of nanoparticles.