The effects of Glomus intrardices on the reproduction of the burrowing nematode Radopholus similis were studied under dixenic culture conditions. The life cycles of both the arbuscular mycorrhizal fungus (AMF) and the nematode were completed in presence of each other and a transformed carrot root as host. The AMF suppressed the R. similis population by almost 50% and thus increased protection of the root against the nematode. This reduction was significant for both females and males within roots. There was no correlation between nematode population density and either AMF interval root colonization, external hyphal development or spore production. These results demonstrate that the dixenic system, although artificial, is a valuable tool for studying AMF-nematode interactions, complementing the classical experimental approaches.