Diagnosing psychogenic non-epileptic seizures (PNES) is a clinical challenge. There is neither a standard in diagnosing PNES nor a comprehensive theoretical framework for this type of seizure. The diagnosis of PNES must be made by excluding epilepsy. However, epilepsy cannot always be determined and PNES and epileptic seizures may coexist. In this study, the characteristics of PNES and patients are discussed. The diagnosis of PNES and epileptic seizures was facilitated by the simultaneous recording of seizures on video tape and EEG. Seizure provoking techniques, hormonal indices, and psychological methods were also used. The benefits and limitations of these techniques are discussed and proposals are made for clinical guidelines.