Six new teleocidin-related compounds (3~8) together with (—)-N13-desmethylindolactam V (9) were found in the culture broth of Streptoverticillium blastmyceticum NA34-17 producing tumor-promoting indole alkaloids. Compounds 3~8 proved to be a dimer of (—)-indolactam V (3), which bound through a methylene group at position 7, 2-oxy derivatives of (—)-indolactam V (4 ~ 7) and 14-O-methylteleocidin A-1 (8), respectively. Their tumor-promoting activities are also discussed. © 1988, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.