The purpose of this study was to verify possible cognitive dysfunction in patients with juvenile myoclonic epilepsy (JME) and its relationship to factors related to epilepsy and schooling. Fifty subjects diagnosed with JME and 50 controls underwent neuropsychological assessment evaluating intellectual functions, attention, memory, executive functions, and language. The patients were further divided into two subgroups on the basis of educational level: < or = 11 and >11 years of formal education. Participants diagnosed with JME scored significantly below age-, education-, and gender-matched controls on neuropsychological measures of attention, immediate verbal memory, mental flexibility, control of inhibition, working memory, processing speed, verbal delayed memory, visual delayed memory, naming, and verbal fluency. A positive correlation was observed between duration of epilepsy and cognitive decline. However, in the group of patients with >11 years of education, this correlation was not significant. In this series of patients with JME, neuropsychological evaluation suggests widespread cognitive dysfunction outside the limits of the frontal lobes. The duration of epilepsy correlated with cognitive decline, and patients with higher education manifested less progression of deficits.