To assess prognostic factors for absence epilepsy (AE), we analyzed data from 80 patients treated for childhood AE (CAE; n = 53) or juvenile AE (JAE; n = 27) in our epilepsy clinic between 1985 and 1992. All patients were classified according to the International Classification of Epileptic Syndromes which was proposed by the International League against Epilepsy in 1989. Patients were separated into two groups based on the course of disease under adequate treatment: Complete response group (CRG): disappearance of absence seizures (AS) or generalized tonic-clonic seizures (GTCS). Poor response group (PRG): persistence of AS and/or GTCS. Approximately 40% of both CAE and JAE patients had poor response. One parameter was associated with poor prognosis in CAE patients, the presence of polyspikes or polyspikes and waves during sleep. No statistical correlation was made for JAE patients. GTCS were frequent in JAE and GTCS occurrence in CAE patients was associated significantly with age at onset after 8 (p < 0.05). The fact that social and educational performance was poorer in the PRG of both types of AE underlines the importance of therapeutic response in patient rehabilitation.