An investigation of the relationships between vitellogenin, 20-hydrozyecdysone and oocyte development of banana shrimp obtained form Kao-Seng beach, Songkhla, indicated that haemolymphatic vitellogenin level varied according to development stages of oocyte. Its levels increased at the stages 1, 2 and attaining its peak with GSI of 5.18 at the termination of stage 3 and subsequently dropped probably due to the absorbtion of bitellogenin into the oocyte. The result complies with the histological study that revealed the presence of rcd-shaped bodies in the ovary of stage 4. It was also found that levels of haemolymphatic vitellogenin were influenced by molting hormone as observed during the molting period. A comparative study of 48-hour duration was undertaken by injecting 20-hydroxyecdysone at doess 50, 100, 150 ng/g, body weight, normal asline injection and eye-stalk ablation, result of which pointed out that the 50 ng dose could elevate the haemolymphatic vitellogenin level whereas at higher doses of 100 and 150 ng, such levels tended to be lowered and eyestalk ablation was more effective in reducing vitel-logenin than hormone injection. No ovary development waqs detected in all treatment. The research finding gave on evidence that 20-hydroxy-ecdysone functions as a secondary factor in banana shrimps ovary development.