Nonepileptic seizures (NES) are commonly observed in patients with seizures resistant to antiepileptic drugs (AEDs). However, NES may be symptomatic of different diagnoses, in particular, conversion disorder (CD) and coexisting NES and epileptic seizures (CENES). We compared the clinical characteristics of these disorders in 219 patients with refractory seizures. The prevalence of NES was similar in children (11%) and adults (16%). In both groups, CENES represented the most frequent cause of NES (75%). In adults, CD was associated with a shorter duration of illness and normal neuroimaging and interictal EEG compared with the other groups. Patients with CD represented one-quarter of all patients with AED-resistant seizures with normal presentation during interictal investigations. In both children and adults with AED-resistant seizures, NES are frequently observed and are three times more likely to be CENES than CD.