Bialaphos (BA) is a metabolite produced by Streptomyces hygroscopicus SF-1293 and is now being in use as a herbicide. Based on the structures of biosynthetic intermediates such as phosphinic or phosphonic acid derivatives, which were produced by blocked mutants, by the addition of monofluoroacetic acid, or accumulated under fermentation conditions minus cobalt ion, its biosynthesis has been assumed to proceed as follows; phosphoenolpyruvate-> phosphinopyruvic acid (formerly called a-keto MP-103) -> 2-phosphinomethylmalate -> deamino a-keto demethylphosphinothricin (formerly called a-keto MP-101)->demethylphosphinothricin (DMPT, formerly called MP-101)-> demethylbialaphos (DMBA, formerly called MP-102)->BA. Recently we have succeeded by mutagenesis with nitrosoguanidine in the isolation of three mutants (NP-51, NP-45 and NP-8) with blocks after DMPT. We wish to report herein their accumulation products and abilities as converters. These data provide detailed information about the late steps in the biosynthetic pathway of BA.