A triazine dye, Cibacron blue 3G-A (CB), is an inhibitor of cell separation of staphylococcal spp. therefore, we examined the effect of CB on growth of gram-positive bacteria other than Staphylococcus. CB added to the medium of growing cultures of strains of genus Micrococcus, Streptococcus, Lactobacillus and Bacillus caused inhibition of cell separation. Moreover, in case of Bacillus and Lactobacillus, individual cells were elongated as filament. Strains of the genus Micrococcus were as sensitive to CB as genus Staphylococcus in which the minimum concentrations of CB needed for inhibition of cell separation ranged from 15 to 100 microM. Other strains belong to genus Streptococcus, Bacillus and Lactobacillus were less sensitive; the minimum concentrations were 100 microM--25 mM.