A wide and diverse range of fungi which feed on nematodes occur in the soil. This is not surprising when one considers the long co-evolution of nematodes and soil fungi which has inevitably occurred in the close confines of the soil habitat. So predaceous and parasitic relationships have evolved amongst most of the major groups of soil fungi from the Phycomycetes to the Basidomycetes.1 Collectively they are known as nematophagous or nematode-destroying fungi, with the term nematode-trapping fungi used to describe predators only. They are natural enemies of nematodes and have developed very sophisticated strategies for either infecting or capturing these small animals. Nematophagous fungi fall into two broad groups, those which parasitize nematodes (endoparasites) with small conidia or zoospores, or those which capture nematodes (predators) using modified hyphal traps. The fate of the nematode will be the same whether infected by an endoparasite or captured by a predator, with fungal hyphae developing within the nematode and the body contents utilized by the fungus. In nature, nematophagous fungi help to recycle carbon, nitrogen, and other important elements from the often considerable biomass of soil nematodes which are feeding on the microbial decomposers. Due to the frequency at which neniatophagous fungi are isolated, it is tempting to surmise that their role of nutrient recycling in the soil is a major one, although it has never been quantified. For man however, the ability of the group to capture and destroy nematodes has presented the attractive possibility of harnessing the fungi as a biological control for this most damaging agricultural pest.