Thirty eight strains of B. subtilis were tested for the presence of antifungal antibiotics of the iturin group. The characterization of these antibiotics was made on the basis of: antifungal activity against P. chrysogenum, isolation and purification of the active substance, quantitative analysis of alpha-aminoacids and identification of the liposoluble dipeptide obtained by partial hydrolysis. The only antibiotics of the iturin group found were: iturin A, mycosubtilin and bacillomycin L.