The effects of the abiotic inducers β-glucan, extracted from Shiitake (Lentinula edodes), BFIICaB^® (Kappaphycus alvarezii) and BKPSGII^® (K. alvarezii X Sargassum sp.) on tomato plants infected with Fusarium oxysporum f. sp. lycopersici (FOL) were evaluated through the activity of enzymes related to the induction of resistance at 5 and 10 days after inoculation (DAI). Tomato plants (21 days old, after germination) were inoculated with the pathogen conidia suspension and sprayed with 0.3% aqueous solutions of the inducers. The activities of the enzymes β-1,3-glucanase, peroxidase and phenylalanine ammonia lyase (PAL) were evaluated in fresh tomato leaves collected at 5 and 10 DAI. In all treatments, peroxidase showed the highest enzymatic activity, followed by β-1,3-glucanase and PAL. Between the seaweeds, the inducers extracted from the red alga Kappaphycus alvarezii (BFIICaB^®) promoted the highest enzymatic activity. The exception was BKPSGII^® (K. alvarezii X Sargassum sp.) where the influence of Sargassum sp. resulted in higher peroxidase activity (4.48 Δab₆₀₀ mg P⁻¹ min⁻¹) in the leaves, 10 DAI. Both the red seaweed K. alvarezii and the brown alga Sargassum sp. promoted activities of β-1,3-glucanase, peroxidase and PAL.