The key to the nine species:M. nitidulum Garman,M. aurolaternatum Garman,M. spinosum (Steindachner),M. asperum Richardson,M. obtusirostrum Taning,M. orientale (Gilbert),M. phengodes (Lutken),M. selenoides Wisner andM. brachygnathum (Bleeker), was prepared for the genusMyctophum, typical surface migrating myctophid fishes, from the Pacific and Indian Oceans. The three species ofM. cuvieri (Castelnau),M. indicus (Day),M. novaeseelandidae (Steindachner) were excluded from the present key, since they have not been reported since they were originally described.M. lychnobium Bolin formsM. spinosumlychnobium complex and was also excluded. The systematic accounts were given for seven species.