The aim of this study was to compare various methods of anti fungal activity determination in model experiments. For the investigations Bacillus coagulans (No. 6) isolate with the high anti fungal activity, isolated from lupine composts was used. Anti fungal activity of the examined isolate was estimated against five pathogenic species of fungi: Rhizoctonia so/ani, Bipolaris sorokiniana, Sclerotinia sclerotiorum, Trichothecium roseum and Fusarium oxysporum. Determination of fungal growth was carried out by three methods: ergosterol assessment, counting colony-forming units (CFU) and agar plate diffusion assay. Statistically significant Spearman's rank coefficients were recorded between ergosterol assessment and two other methods. On the basis of this data the assessment of ergosterol is the best way ofdetermination of antifungal activity and may be used as a reference procedure.