The antibiotics synthesis suppression (abs) mutants have pleiotrophic effect on the synthesis of all four S. coelicolor`s antibiotics. For the aim of understanding the differentiation of streptomyces and the regulation of antibiotics synthesis, we isolated a new type of abs mutant namely abs95 mutant whose characteristic is quite different from know absa and absB mutants. abs95 mutant does not produce any antibiotics on rich R2YE plate. However, on the minimal plate, it could not grow well and produced pigmented antibiotics in some degree. In absA or absB background, the activity of xylE reporter gene which is transcriptionally fused to actinorhodin (one of the antibiotics S. coelicolor produce) biosynthetic operon was reported as negligable. The result leads to the suggestion that the molecular basis of antibiotic synthesis suppression in abs might be on transcriptional level. However, the xylE activity of abs95 mutant strain with the transcriptional fusion was not negligable. Moreover when the act II/ORFIV gene which is the positive activator of transcription of act operon was introduced into the abs95 mutant strain in the form of high copy number plasmid, we found a little actinorhodin production. The same segment was introduced in absB and the strain produced actinorhodin in large quantity. Such data suggests another regulation point other than transcriptional one might be operate in abs system.