 This is a world wide, multicenter, randomized, double-blind, placebo-controlled study to evaluate the tolerability, safety and efficacy of 3 target doses 5, 15, and 25 mgkgday of topiramate compared with placebo as an adjunct therapy in infants with refractory partial onset seizures POS. There are 4 phases to the study, a screening phase of 3 days, a double blind treatment phase of 20 days, a one year open label extension phase and a posttreatment taper and withdrawal phase. The oral liquid formulation will also be assessed during this study, as it is investigational, unlike the marketed sprinkle formulation. 5, 15, 25 mgkgday of topriramate sprinkle and oral liquid formulation will be administered during the four phases of the study. 