Objective: To monitor the difference in conversion rates to multiple sclerosis (MS) in 46 patients with optic neuritis between patients with multifocal visual evoked potential latency delay and those with normal latency. Design: Prospective case series. Setting: Metropolitan neuro-ophthalmology clinic. Participants: Forty-six patients with optic neuritis who did not have a diagnosis of MS on enrollment in the study. Main Outcome Measures: Conversion to MS according to the McDonald criteria. Results: Analysis revealed that only 22 subjects had multifocal visual evoked potential latency delay. Over 1 year, 36.4% of patients with optic neuritis with latency delays progressed clinically to MS compared with 0% of those with normal latencies (P = .03, X²). Conclusion: This may indicate that multifocal visual evoked potential latency delay can assist in predicting progression to future MS.