Electron microscopic studies of the interaction of second-stage juveniles ofMeloidogyne hapla andArthrobotrys oligospora (CBS 289.82) strongly suggest that hyphae attachment to nematodes was mediated by a 0.1μm thick layer matrix between the fungus and prey after contact with the nematode cuticle. The amorphous electron opaque matrix was irregularly distributed over the fungal surface, in some cases covering only the side attached to the nematode. Serial sections of adhesive hyphae showed that the extracellular matrix spread from the exact site of capture. A matrix with this thickness was never observed in the absence of nematodes.