Background: Although epileptic seizures occur more commonly in older adults, their occurrence in this age group is often unexplained. One unexplored precipitant of seizures in older adults is obstructive sleep apnea ( OSA), which is also more common in this age group. Our objective was to investigate whether OSA is associated with seizure exacerbation in older adults with epilepsy. Methods: Polysomnography was performed in older adult patients with late-onset or worsening seizures ( Group 1, n = 11) and those who were seizure-free or who had improvement of seizures ( Group 2, n = 10). Results: Patients in Group 1 had a significantly higher apnea-hypopnea index than patients in Group 2 ( p = 0.002). Group 1 patients also had higher Epworth Sleepiness Scale scores ( p = 0.009) and higher scores on the Sleep Apnea Scale of the Sleep Disorders Questionnaire ( p = 0.04). The two groups were similar in age, body mass index, neck circumference, number of antiepileptic drugs currently used, and frequency of nocturnal seizures. Conclusions: Obstructive sleep apnea is associated with seizure exacerbation in older adults with epilepsy, and its treatment may represent an important avenue for improving seizure control in this population.