目的　探讨亚临床发作对癫痫患儿认知功能的影响。方法　对 2 7例服用单药治疗、近期无临床发作的原发性癫痫患儿及 11例正常儿童进行神经心理测验及事件相关电位P3测定。依据测验中EEG结果将癫痫患儿分为亚临床发作组及无亚临床发作组。比较三组间各认知功能指标的差异。结果　亚临床发作癫痫组较无亚临床发作组总智商低 ,且汉字结构辨认P3潜伏期延长 ;无亚临床发作癫痫组较正常组汉字结构辨认P3波幅低 ;未发现P3潜伏期与总智商之间具有相关性。结论　亚临床发作可影响癫痫患儿的认知功能。汉字结构辨认P3潜伏期是反映认知功能的敏感指标 Objective To investigate the impact of subclinical seizures on cognitive function in children with epilepsy. Methods Twenty-seven patients with primary epilepsy and 11 normal children who were treated with monotherapy and without clinical seizure were subjected to neuropsychological test and event-related potential P3. Based on the EEG results of the test, children with epilepsy were divided into subclinical group and non-subclinical group. The difference of each cognitive function between the three groups was compared. Results The sub-clinical seizure epilepsy group had lower total IQ than the non-clinical seizure group, and P3 latency was longer than that of the normal seizure group. P3 amplitude was lower than that of the normal group in the subclinical epilepsy group. P3 latency was not found between the latency and total IQ Correlation. Conclusion Sub-clinical seizures may affect the cognitive function of children with epilepsy. Chinese character structure recognition P3 latency is a sensitive indicator of cognitive function