Conidiospores of the endoparasitic fungus Drechmeria coniospora attach exclusively to chemosensory organs of nematodes. Starting from the chemosensory organ trophic hyphae penetrate the victim. The infection process proceeds in serveral phases as shown by means of electron microscopy. Time-lapse sequences document the series of events of the infection process, the outgrowth of conidiophores through the host's cuticle, and the release of new spores.