Exploration of subjective experiences during seizures may enhance knowledge of the differing natures of epilepsy and nonepileptic attack disorder (NEAD). We performed a quantitative evaluation of both the general level of awareness and the specific contents of consciousness during seizures using the Ictal Consciousness Inventory (ICI). Ninety-five adult outpatients attending general neuropsychiatry and epilepsy clinics with established diagnoses of either epilepsy (n=66) or NEAD (n=29) completed one ICI for each witnessed seizure recalled. Patients with a dubious/dual diagnosis were excluded. ICI Level (ICI-L) and ICI Content (ICI-L) scores were calculated for the 167 questionnaires generated by patients with epilepsy (n=119, of which 58 from patients with temporal lobe epilepsy, 14 frontal lobe epilepsy, and 47 idiopathic 30 generalized epilepsy) and patients with NEAD (n=48). Mann-Whitney U tests revealed statistically significant higher ICI-L and ICI-C scores for patients with NEAD (both P=0.01). Subjective reports of consciousness experiences varied between epilepsy and NEAD, with patients with NEAD reporting significantly greater levels of general awareness/responsiveness and more vivid subjective experiences during attacks. The ICI is proposed as a potentially useful self-report instrument to supplement clinical and instrumental tests for the differential diagnosis of epilepsy and NEAD.