Abstract: Eyestalk-ablation is used usually to induce ovarian maturation in Penaeus monodon. Wild P.monodon females were obtained from the sea around Sanya, weighted 149.525.8 g. Serotonin solution was injected into broodstock at 50 gg-1 body weight on the 1st, 5th, 10th day. Survival and hatching rate were significantly higher in serotonin-injected females than unilateral eyestalk-ablated shrimp. But the time to the first spawning event from the beginning of treatment was shorter for eyestalk-ablated females. Gonad somatic index (GSI) in serotonin-injected and eyestalk-ablated groups were both significantly higher than the control. The results suggested that stimulation of serotonin can enhance the ovarian maturation of P.monodon.