In the course of screening for new bioactive compounds, we have isolated two antibiotics from the fermentation broth of Streptomyces sp. TC 1190 and were designated TMC-135A and B. Spectroscopic analyses revealed that TMC-135s were new members of triene-ansamycins, closely related to thiazinotrienomycins and cytotrienins. This paper briefly describes the taxonomy, isolation, physico-chemical properties, structure elucidation and biological activity of TMC-135A and B.