tAn epidemic with a high mortality rate (80–100%) recently occurred in the cultured Chinese mittencrab, Eriocheir sinensis, which is a very important economic crustacean species in China. Using negativestain, histopathology and nested PCR supplemented by sequencing we identified white spot syndromevirus (WSSV) in these crabs. Challenge experiments revealed that the disease was caused by WSSV andconfirmed the crab’s susceptibility to this virus, which was consistent with previous laboratory-basedstudies. A cumulative mortality of 100% was observed within 10 days post WSSV injection. This is thefirst report of WSSV-associated disease outbreaks in the Chinese mitten crab, which is normally reportedas an important penaeid-shrimp viral pathogen. Furthermore, this is only the second report to describe asignificant pathogen in pond-cultured E. sinensis. These results will enhance the early diagnosis of WSSVin the crab farms and help in monitoring efforts directed at determining the prevalence of the virus in E.sinensis.