Eucithara vexillum is a small sea snail, a marine gastropod mollusk in the family Mangeliidae.

[1] The length of the shell attains 11 mm.

The entire surface of the shell is decussately striated, as if very finely granulated.

The color of the shell is orange-yellow, with a number of narrow whitish bands.

[2] This marine species occurs in the Central Pacific off Fiji.