In the course of our examination for the alkaloid productivities of Streptomyces strains, Streptomyces sp. NA-15 was found to produce a new alkaloid, pyrindicin, in the culture medium. The strain NA-15 was found to be a variant of Streptomyces griseoflavus and was designated as S. griseoflavus var. pyrindicus nov. var. n After the culture conditions for pyrindicin production were studied, pyrindicin was obtained as its hydrochloride (mp 145°C, decomp.) from the cultured broth. The compound was shown to possess weak antimicrobial and several pharmacological activities. The LD50of the hydrochloride (ip, in mice) was 87 mg/kg. © 1974 Taylor & Francis Group, LLC.