Aquatic Conservation. Analysis of the resistance of heterosis in Fenneropenaeus chinensis to natural infection with white spot syndrome virus. A selected population of the shrimp (Fenneropenaeus chinensis) was tagged, which included 42 full-sib families. A sample of 40 tagged test animals per family was infected by WSSV without hominine help. A week later, the surviving animals were taken out and then the survival rate per family was calculated. The virus positive rate of white-spot syndrome per family was detected by nested-PCR (Polymerase Chain Reaction) for every survivor. Comparison was carried out between pairs of families mainly in terms of the survival rates and the conclusion as follows: 4 families’ survival rates were over 60 percent and 7 families’survival rates were under 20 percent. The analysis of correlation among the indexes indicated that the relationship between the survival rate and the virus positive rate of the first-step and second-step PCR was negative correlation and not significantly different. However, there was positive correlation and significant difference between the virus positive rate of the first-step and the second-step PCR. The analysis was carried out depending on both the survival rate and the virus positive rate and the results as follows: one self-fertilized family of Qingdao population and one hybridized family between the cultured family population of Korea(♂) and Rushan population (♀) were much better than those of the others in resistance to WSSV. There were no significant differences between pairs of cross combinations in the survival rate, which were analysed by independent-sample T test. So the family selection probably was the main method for culturing WSSV-resistant breed. The cross combinations were analysed by multiple comparison method and the result showed: there was difference between the cross combination of the cultured family population of Korea(♂)and Rushan wild population (♀)(56.20%±8.75%) compared with the self-fertilized combinations of the cultured family population of Korea (P<0.05) in resistance to WSSV, which showed the cross combination could get the heterosis. However, there was great difference between the cross combination of the Rushan wild population(♂) and the cultured family population of Korea(♀) compared with their reciprocal hybrids in heterosis. 15 Refs.In Chinese. Key words:Fenneropenaeus chinensis; nested-PCR; white-spot syndrome virus (WSSV) LI Su-hong(Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China), ZHANG Tian-shi, MENG Xian-hong, KONG Jie //J Fish China,2007,31(1).68-75