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 149.5±25.8 g. Serotonin solution was injected into broodstock at 50 μg · g^-1 body weight on the 1^st, 5^th, 10^th 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.