During the last few years the Dutch species of nudibranchs have been examined for parasitic or semi-parasitic copepods. Up to now only one species — Lichomolgus agilis (Leydig) (fig. 1) — has been found, from the gills of Aeolidia papillosa (L.), captured in two different localities. This species is new to the Dutch fauna. It is by no means common in Dutch waters; I examined several hundreds of Aeolidia ’s and a considerable number of other Dutch nudibranchs, e.g. Lamellidoris bilamellata, Goniodoris castanea, Acanthodoris pilosa, Tergipes despectus and Eubranchus exiguus without finding a single copepod.