The concentrations of progesterone and estradiol in hepatopancreas, ovar y, hemolymph of Penaeus chinensis were investigated by means of radioimmunoassay during a reproductive cycle, and changes in GSI ( gonado somatic index) and HSI( hepatosomatic index) were monitored. Progesterone and estradiol were detected in the hepatopancreas, o vary, and hemolymph of the shrimp with maturing or matured ovary . During immature stage ( length< 8- 10cm ) , the two hormones were undetectable, however, during previtello genesis stage ( perinucleolus stage, length> 11- 13cm) , the concentrations of both hormones in three tissues increased rapidly, and estradiol in ovary reached a peak ( 450? 86. 7pg/ g) . During vitellogenesis stage ( length> 13- 15cm) , the tw o hormones maintained relatively high levels. Progesterone reached peaks in ovary ( 1975. 1? 175. 2pg/ g ) , and hepatopancreas ( 902. 6 ? 130. 5 pg/ g) , and estradiol reached a peak in hemolymph ( 451. 3 ? 73. 7 pg/ ml) . The hormone level decreased sharply during maturation stage, and in hepatopancreas, the hormones even became undetectable. During whole reproductive cycle, GSI increased continuously and HSI stopped increasing during maturation stage, and showed a similar change like that of hormone levels in hepatopancreas and o vary. The results suggested that hepatopancreas might be the site of vitellogenin synthesis in P. chinensis .