Few reports on population-based studies of birth rate among epilepsy patients have been published. In most previous studies, fertility has been lower among epilepsy patients than in the rest of the population. However, conflicting results have also been reported. Because of small samples and selective material, the generalizability of these results is also limited. The authors conducted a population-based cohort study of birth rate (1985-2001) in a nationwide Finnish cohort of patients with newly diagnosed epilepsy and a population-based reference cohort. All patients (n = 14,077) approved as eligible for reimbursement for antiepileptic medication from the Social Insurance Institution of Finland (KELA) for the first time between 1985 and 1994 were identified from the KELA database. A reference cohort (n = 29,828) was identified from the Finnish Population Register Center, with frequency-matching on age. Information on follow-up status and livebirths were also obtained from the Finnish Population Register Center. The birth rate was lower in patients with epilepsy than in the reference cohort among both men (hazard ratio = 0.58, 95% confidence interval: 0.54, 0.62) and women (hazard ratio = 0.88, 95% confidence interval: 0.83, 0.93). There were a clear decreasing trend by age at observation in men with epilepsy and a moderate decreasing trend by age at start of follow-up in women with epilepsy.