Teleocidins produced by actinomycetes are potent tumor promoters in mouse skin carcinogenesis. Among the teleocidin-producing actinomycetes, Streptoverticillium blastmyceticum NA34-1 has the characteristic feature of producing (-)-indolactam V (1), the possible biosynthetic intermediate of teleocidins, in quantity. In previous publications, we reported the isolation and structural identification of several important teleocidin-related compounds from this actinomycete. These compounds contributed to the research on the structure-activity relationship, metabolism, and biosynthesis of teleocidins. Our continuous search to discover new teleocidin-related compounds have recently resulted in the isolation of N13 desmethylteleocidin A-l (2) from the mycelia of this actinomycete together with N13-desmethylteleocidin B-4 (3), which has been isolated from S. olivoreticuli by Sakai et al. This paper describes the isolation and biological activities of these compounds (2 and 3). The contribution of the N13-methyl group of teleocidins to their activities and the metabolism of teleocidins by rat liver microsomes are also mentioned.