In Uganda, banana (Musa spp.) production is constrained by the burrowing nematode Radopholus similis. Non-pathogenic, endophytic Fusarium oxysporum has been isolated from healthy banana plants, and several strains have shown potential as biological control agents against R. similis. Plant infection by R. similis can be characterised in three steps: host searching, root penetration and reproduction. In this study, we investigated the effects of three endophytic F. oxysporum strains (Eny1.31i, Eny7.11o and V5w2) on root penetration and reproduction of R. similis in tissue culture-derived banana plants. The number of R. similis that penetrated roots of endophyte-inoculated and untreated plants was not influenced by the endophytes in either laboratory or screenhouse experiments. However, R. similis reproduction was reduced by endophytes. Strain V5w2 gave the greatest suppression of R. similis reproduction. The results of this study imply that antagonism of endophytic F. oxysporum against R. similis in banana plants is post-infectional and mediated through disruption of nematode reproduction.