The purpose of this study is to describe clinical and electrophysiological findings of three patients with unilateral extensive peripapillary myelinated nerve fibers. Three patients with unilateral extensive peripapillary myelinated nerve fibers were examined. A complete ophthalmologic examination including uncorrected and best spectacle corrected visual acuities (UCVA, BSCVA) on Snellen charts, dilated fundoscopy, fundus fluorescein angiography (FFA), optical coherence tomography (OCT), perimetry and electrophysiological tests was performed. ERG results of both eyes were normal in all cases. FFA showed hypofluorescence at the myelinated nerve fibers (MNF) area in the affected eyes. We found a visual field defect resembling arcuat scotom at perimetry of the affected eyes. In OCT, there was hyper-reflectivity in reply to MNF. In all cases, pattern ERG results of the affected eyes showed decreased amplitudes and increased latencies of P50 and N95 waves. P100 amplitudes of PVER and FVER were decreased, and latencies were increased in all affected eyes. Extensive peripapillary myelinated nerve fibers may cause changes in PERG and VER.