Olfactory event-related potentials (OERP) have been used to investigate olfactory processing in health and disease. However, the reliability of the OERP has yet to be established statistically. The present study examined test–retest reliability of the OERP over a 4-week interval. EEG was recorded from Fz, Cz, and Pz, using a single-stimulus paradigm with amyl acetate. Reliabilities for ERP component latencies and interpeak amplitudes were assessed as intraclass and Pearson product-moment correlation coefficients. Reliabilities were higher for latency than for amplitude. Highest correlation coefficients were observed for P2 latency, specifically at Cz and Pz P3 amplitude and latency exhibited high reliability at Cz and Pz. Fz demonstrated weakest correlation coefficients. The data suggest that OERP reliability is comparable to that of auditory and visual ERPs, supporting the use of OERPs in both basic research and clinical assessment.