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A strain of Streptomyces nigrifaciens (p-9) was isolated from marine sediments. Morphological, cultural, biochemical and cell wall analyses were made to identify the strain. Glycerol, glucose, sucrose, lactose and maltose as carbon sources, and soybean meal, yeast extract, malt extract, peptone and sodium nitrate as nitrogen sources were used to select the best medium for maximum production of antibiotics. Glucose and soybean meal were the best carbon and nitrogen sources, respectively, for maximum antibiotic production. Ethyl acetate, n-butanol, dichloromethane, petroleum spirit and benzene were used for extraction. Ethyl acetate extract showed significant activity against both gram positive and gram negative bacteria. Streptomyces nigrifaciens (p-9) differs significantly from the type strain in antibacterial activity.