In the screening programme of marine actinomycetes for potent antagonistic agents, 16 isolates were isolated from Marine sediments of Hamsaladeevi, Nizampatnam, Kothapudi, Machilipatnam (Bay of Bengal) in Guntur and Krishna districts of A.P., India. Out of the sixteen isolates subjected to secondary screening, six isolates were exhibited antibacterial and antifungal activities against Salmonella typhi, Corynebacterium diphtheriae, Klebsiella pneumoniae, Bacillus subtilis, Escheriae coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger, Rhizopus spp. All six isolates were highly active with an inhibition zone more than 25 mm in diameter. Analysis of its spore morphology, structure of spore chain and physiological characteristics, all six isolates were assigned to the genus Streptomyces. All Streptomyces spp., showed antibacterial, anti candidal and antifungal activities. Out of which, two isolates showed excellent antagonistic activity (> 30 mm diameter) against pathogenic microorganisms tested. These two dominant Streptomyces strains are selected and morphological, physiological, biochemical characterization and growth pattern are studied. Altogether, the results of antimicrobial activities produced by these strains clearly indicated that the marine environment is a good harbour for isolation of novel varieties of antagonistic Streptomyces and production of broad spectrum antibiotics.