From July to October in 1987 an epizootic disease occurred in theprawn farm of Pingtan island, Fujian Province. The acute infected disease wasdescribed as "red leg disease" locally, which was characterized by heart and nearbyregion becoming light orange, pleopods red and swimming activity reducing. Thekemolyph drawn from heart of diseased shrimp was thin, turbid and unclottable.The mortality due to this disease was over 90% in shrimp stock. Five strains wereisolated from hemolymph of moribund shrimps. Infection experiments ascertainedthat the bacterial isolates were the cause of the disease. All bacterial isolates showed Gram-negative short rods with a single polarflagellum. They produced acid but no gas from glucose. Moreover, they were oxida-se-positive and could not grow in peptone water lacking NaCl or containing 8%NaCl, or at 42℃. But they grew well in peptone water containing 3 or 6% NaCl.Test for the decarboxylation of lysine and ornithine were negative and argininepositive. All strains were sensitive to vibriostatic agent 0/129. The organisms were identified as Vibrio anguillarum, which was first reported in China as the causativeagent of prawn disease.