The diagnosis of a first seizure or epilepsy may be subject to interobserver variation and inaccuracy with possibly far-reaching consequences for the patients involved. We reviewed the current literature. Studies on the interobserver variation of the diagnosis of a first seizure show that such a diagnosis is subject to considerable interobserver disagreement. Interpretation of the electroencephalogram (EEG) findings is also subject to interobserver disagreement and is influenced by the threshold of the reader to classify EEG findings as epileptiform. The accuracy of the diagnosis of epilepsy varies from a misdiagnosis rate of 5% in a prospective childhood epilepsy study in which the diagnosis was made by a panel of three experienced pediatric neurologists to at least 23% in a British population-based study, and may be even higher in everyday practice. The level of experience of the treating physician plays an important role. The EEG may be helpful but one should be reluctant to make a diagnosis of epilepsy mainly on the EEG findings without a reasonable clinical suspicion based on the history. Being aware of the possible interobserver variation and inaccuracy, adopting a systematic approach to the diagnostic process, and timely referral to specialized care may be helpful to prevent the misdiagnosis of epilepsy.