An antibiotic weakly active against Candida was isolated as a colorless crystalline hydrochloride from a culture of a streptomyces which showed some resemblances with Streptomyces eurythermits. This antibiotic was unstable to acid and alkali, but was recovered in good yield by elution with 0.5M ammoniumchloride solution from the ion-exchange resin, Amberlite IRC-50 (Na+ type). It was determined to be acrylamidine by spectroscopic data, degradation and direct comparison with a synthetic sample. The LD50 (mice) of acrylamidine was 44 mg/kg intravenously. In the course of screening studies for anti-Candida substances, a streptomyces, designated strain No. D274-2 in the authors' laboratory, produced an antibiotic weakly active against a limited number of fungi. The antibiotic was labile in acidic and alkaline solutions, and was determined to be acrylamidine. In this report, characteristics of the producing strain, the processes of production, isolation, and the identification of the antibiotic are described.