One leptocephalus (TL 59.9 mm) from the family Ophichthidae collected from Jeju Island, Korea, was identified using morphological and molecular methods. Our ophichthid leptocephalus was identified as belonging to the genus Muraenichthys based on morphological characters: 157 myomeres; the origin of the dorsal fin located a little in front of the anus; a distinct melanophore present on the opercle; and six gut swellings present. An analysis of 886 base pairs of the 12S rRNA mtDNA sequences showed that our leptocephalus must be Muraenichthys gymnopterus, because its sequences were concordant with those of an adult M. gymnopterus (d=0.001) and next to those of Muraenichthys sp. leptocephalus (d=0.034). Here, we are the first to describe the morphological characteristics of the M. gymnopterus leptocephalus.