The ability of antagonistic Fusarium spp. to control Fusarium wilt of basil caused by F. oxysporum f. sp. basilica was tested under glasshouse conditions from 1994 to 1996. Fusarium oxysporum antagonistic strain 251/2, a protoplast fusion-derived hybrid coded FI-11 and F. moniliforme strains TF4 and TF4 RB were able to decrease (P = 0.05) the incidence of Fusarium wilt significantly. Biocontrol was consistent, especially when the antagonists were applied by mixing a talc preparation of propagules in the substrate (10 5 CFU/ml of substrate) 1–2 weeks before sowing or at sowing. Seed coating with the biocontrol strains (10 8 CFU/g of seed) did not generally provide sufficient disease containment, whereas the combination of substrate treatment and seed coating did not improve wilt control in comparison with substrate treatment alone. Two commercial formulations, based on antagonistic F. oxysporum strains and one containing the antagonistic strain K61 of Streptomyces griseoviridis , were generally not sufficiently effective at the tested dosages.