A marine bacterial strain, Pseudomonas I-2, produced inhibitory compounds against shrimp pathogenic vibrios including Vibrio harveyi, V. fluvialis, V. parahaemolyticus, V. damsela and V. vulnificus. The inhibitory substance was found to be a low molecular weight compound, heat stable, soluble in chloroform and resistant to proteolytic enzymes. The chloroform extract brought down V. harveyi levels in water by over a log unit when applied at 20 μg/ml while the extract did not affect shrimp larvae even at 50 μg/ml level. This marine Pseudomonas I-2 has potential applications for control of shrimp pathogenic vibrios in aquaculture systems.