Objective: The purpose of this study was to examine the open-set word recognition performance of Mandarin Chinese-speaking children who had received a multichannel cochlear implant (CI) and examine the effects of lexical characteristics and demographic factors (i.e., age at implantation and duration of implant use) on Mandarin Chinese open-set word recognition in these children. Design: Participants were 230 prelingually deafened children with CIs. Age at implantation ranged from 0.9 to 16.0 years, with a mean of 3.9 years. The Standard-Chinese version of the Monosyllabic Lexical Neighborhood test and the Multisyllabic Lexical Neighborhood test were used to evaluate the open-set word identification abilities of the children. A two-way analysis of variance was performed to delineate the lexical effects on the open-set word identification, with word difficulty and syllable length as the two main factors. The effects of age at implantation and duration of implant use on open-set, word-recognition performance were examined using correlational/regressional models. Results: First, the average percent-correct scores for the disyllabic "easy" list, disyllabic "hard" list, monosyllabic "easy" list, and monosyllabic "hard" list were 65.0%, 51.3%, 58.9%, and 46.2%, respectively. For both the easy and hard lists, the percentage of words correctly identified was higher for disyllabic words than for monosyllabic words, Second, the CI group scored 26.3%, 31.3%, and 18.8 % points lower than their hearing-age-matched normal-hearing peers for 4, 5, and 6 years of hearing age, respectively. The corresponding gaps between the CI group and the chronological-age-matched normal-hearing group were 47.6, 49.6, and 42.4, respectively. The individual variations in performance were much greater in the CI group than in the normal-hearing group, Third, the children exhibited steady improvements in performance as the duration of implant use increased, especially 1 to 6 years postimplantation. Last, age at implantation had significant effects on postimplantation word-recognition performance. The benefit of early implantation was particularly evident in children 5 years old or younger. Conclusions: First, Mandarin Chinese-speaking pediatric CI users' open-set word recognition was influenced by the lexical characteristics of the stimuli. The score was higher for easy words than for hard words and was higher for disyllabic words than for monosyllabic words, Second, Mandarin-Chinese-speaking pediatric CI users exhibited steady progress in open-set word recognition as the duration of implant use increased. However, the present study also demonstrated that, even after 6 years of CI use, there was a significant deficit in open-set, word-recognition performance in the CI children compared with their normal-hearing peers. Third, age at implantation had significant effects on open-set, word-recognition performance. Early implanted children exhibited better performance than children implanted later. (Ear & Hearing 2013;34;221-228)