Abstract: The results of the investigation on the harpacticoid fauna in the cave Lân Hoang of Northern Vietnam are reported. Two species — Elaphoidella bidens (Schmeil, 1894) and Onychocamptus mohammed (Blanchard & Richard, 1891) are new for the hydrofauna of Northern Vietnam. The taxonomic status of Elaphoidella bidens from North Vietnam is revised. Detailed description as a review of all-important variable characteristics is presented.