Thirty-eight congenitally deaf children received the Nucleus multichannel cochlear prosthesis at NYU Medical Center prior to age five. Preoperative and postoperative evaluations included pure tone audiometry under earphones, warble tone audiometry in the sound field (amplification system preoperatively and implant postoperatively), and open set measures of word/sentence recognition. Tests administered included, but were not limited to, GASP words and sentences, PBK words (scored as words and phonemes) and Indiana phrases and were administered preoperatively and 6, 12, 18, 24, 36, 48, and 60 months postoperatively. Results indicated a significant improvement over time in the ability of the children to perceive words and sentences in the implant only condition. Percent correct scores improved with length of usage and increasing age, reflecting increased ability of the young children to perform the necessary tasks, in addition to developing speech recognition abilities. After using the device for two or more years the children had varying degrees of open set speech perception. These results demonstrate significant improvement in open set speech perception in congenitally deaf children implanted below the age of five.