The changes of progesterone contents of ovary and mandibular organ in crayfish, Procambarus clarkii during the vitellogenesls were studled by using of radioimmunoassay. The progesterone contents increased at early second vitellogenesis stage and decreased significantly at the mid second vitellogenesis stage; the progesterone content of post spawning stage was undetective. These results indicated that the ovarian progesterone contents decreased during the mid second vitellogenesis, maturation and spawning. These findings suggest that progesterone content increase is related to the onset of the vitellogenesis. The progesterone content in mandiburlar organs at different developing stage was all undetective.