Abstract: Mass mortality of shrimp Litopenaeus vanmamei occurred in shrimp fams in a coastal city,Zhangpu Coun-ty,Fujian Province,from June to September,2012.The disease outbreak caused heavily economicloss to shrimpculture industry.The symptom of infected shrimps showed a swelled and whitened hepatopancreas and empty intes-tine,with mortality over 50%.Bacteria were isolated from the hepatopancreas of infected shrimps,with a dominantone designated as strain 1937.Based on 16S RNA and multilocus sequence analysis(poD,toxR and poA gene),strain 1937 was identified as Vibrio parahaemolyticus.What's more,the haemolysin gene(zlh)specific to V.para-haemolyticus was also detected in strain 1937.Pathogenicity test byimmersion infection confimed that strain 1937was viulent to Litopenaeus vannamei post larvae and adults,and the LC,value was 1.33×10⁶cfu/cm³and1.42×10⁶cfu/cm³,respectively.The symptom of the shrimps challenged with bacterial strain1937 demonstratedthe same as the ones in shrimp fams.Thus,V.parahaemolyticus strain 1937 was proposed as the causative agentfor this disease outbreak of shrimp Litopenaeus tamamei.