Two new teleocidin-related metabolites, (-)-7-geranylindolactam-V [2] and blastmycetin F [3], were isolated from fermentation broths of the actinomycete Streptoverticillium blastmyceticum NA34-17, and their structures were determined by spectroscopic methods. Compound 2 bound strongly to phorbol ester receptors in a mouse epidermal particulate fraction, suggesting that it is a potent in vivo tumor promoter comparable to teleocidins A-1 [4] and B-4 [5]. The teleocidins (1-5) are unusual indole alkaloids containing a nine-membered lactam ring and a complex monoterpenoid moiety, which act as potent skin tumor promoters (6). Several teleocidin-producing organisms (actinomycetes and blue-green algae) have been previously reported (7,8). Among these organisms, the actinomycete Streptoverticillium blastmyceticum NA34-17 (9,10) is unique in producing (-)-indolactam-V [1] (11) in quantity, in addition to minor components. In previous publications we have reported the isolation of several teleocidin-related compounds from this actinomycete (12-15), which have contributed to research on structure-activity relationships (16,17), metabolism in mammals (18), and teleocidin biosynthesis (19,20). Our continuing research aim to discover new teleocidin-related compounds has resulted in the isolation of (-)-7-geranylindolactam-V [2] and blastmycetin F [3] from S. blastmyceticum. This paper describes the isolation, structural determination, and biological activities of these new metabolites.