The complete interneural insertion patterns were reported for the seven members of the genus Lethrinus (Lethrinidae) inhabiting the Red Sea coasts of the Republic of Yemen and compared with eight Lethrinus species obtained from different parts of the world. Over 190 specimens, representing 14 species of the genus Lethrinus, were used in the present study. The results showed that the pattern of the dorsal fin pterygiophores in anatomical relation to the vertebrae exhibits intraspecific stability. Therefore, it was possible to develop a key to differentiate the 14 Lethrinus species obtained from various parts of the world. Three supraneural spines were found in only 11 species, with three spines located anterior to the neural spine of the first vertebra.