A peptide antibiotic, edeine B(1), exerts a lethal action in Bacillus subtilis causing filamentous morphology. This antibiotic assumes to inhibit cell division by interacting with FtsZ and inhibiting FtsZ polymerization. The temperature-sensitive mutant ftsZ ts1 was shown to be hypersensitive to the antibiotic as compared to the parent 168 with respect to its lethal action and the sensitivity to the antibiotic of the revertant of ftsZ ts1 was shown to be intermediate between those of the parent 168 and the ftsZ ts1. Alteration of FtsZ sequence may be responsible for sensitivity to edeine B(1). The residues at 240, 278, 345 and 346 in the FtsZ sequence of the parent 168 were A240, A278, D345 and A346. Those of ftsZ ts1 were V240, V278, E345 and P346. Those of the revertant of ftsZ ts1 were A240, A278, E345 and P346. The difference in sensitivity to edeine B(1) among these strains is presumably due to the difference in the residues at 240, 278, 345 and 346 in the FtsZ sequence. The sequential events of the inhibition of FtsZ assembly and the inhibition of protein biosynthesis by edeine B(1) may progress synergistically, resulting in cell death.