Quinaldopeptin, a new type of quinomycin antibiotic, was isolated from the culture of Streptoverticillium album strain Q132-6. The antibiotic exhibited strong in vitro antimicrobial and cytotoxic activity and significantly prolonged the survival time of mice inoculated with a murine tumor. Quinaldopeptin is a symmetric cyclic peptide linked only by peptide bonds and differs from known antibiotics of the quinomycin family by the lack of ester linkage.