This study examined the effects of different mode of administration of LHRH-A on spermiation in the red spotted grouper （ Epinephelus akaara ）. Groups of red spotted grouper received either saline injection on 0, 7 day （ C, 50μg?kg^-1 body weight [BW] ） or LHRH-A injection on 0, 7 day（ IN, 50μg?kg^-1 body weight [BW] ） or a slower-releasing implant（ IM, 100μg? kg^-1 body weight [BW] ）. Serum levels of the androgens testosterone （T） and 11-ketotestosteron （11-KT） were significantly affected by the sustained LHRH-A delivery systems, serum T and 11-KT levels increased rapidly after being implanted. These results indicated a close correlation between sustained stimulation of T and 11-KT release, achieved by LHRH-A delivery systems, and long-term enhancement of milt production. Histological evaluation of the testes indicated that, by day 21, control and injection fish testes contained almost exclusively spermatozoa. At the same time, testes from LHRH-A implanted fish still contained large numbers of spermatozoa in the testes, indicating that spermiation was still underway. Over 40 days experimental period a total of milt volume as follows ： controls 〈 injection 〈 implantation. LHRH-A treatments stimulated a significant increase in total milt volume. While milt volumes in injected males returned to control values by day 14, implanting treated with sustained LHRH-A delivery systems maintained significantly elevated milt volumes for 40 days. Sperm motility tended to be positively correlated with milt volume, and there were no significant differences in sperm counts. These data show that sustained administration of LHRH-A significantly increases and prolongs spermiation in the red-spotted grouper without altering sperm concentration or quality.