Mexichromis trilineata is a colourful species of sea slug, specifically a dorid nudibranch.

[5] Mexichromis trilineata has been found in Sumbawa, Sulawesi and Bali, Indonesia; the Philippines, the South China Sea, Heron Island, Great Barrier Reef and Queensland, Australia.

[7] Mexichromis trilineata have three yellow longitudinal bands outlined in white, with the entire mantle edged with a fine white line.

[8] The gills and rhinophores are typically violet at their bases and then translucent white with red markings.

Some specimens have yellow or orange markings on the white lines.