The object of this study was to examine the effects of exogenous and endogenous prostaglandin E2 (PGE2) on the sexual behavior of female South African clawed frogs, Xenopus laevis. Ticking and leg extension, which communicate sexual unreceptivity to males, were studied in intact, ovariectomized, and ovariectomized-oviductectomized females. The onset of the PGE2 behavioral effect occurs within 30 sec to 3 min of injection for intact and ovariectomized females; for ovariectomized-oviductectomized females, the latency period for the effect ranges from 10-20 min. PGE2 induced receptivity in doses as low as 0.03 microgram/frog. Injection of the prostaglandin synthesis inhibitors, indomethacin and flurbiprofen (FBP), blocked chorionic gonadotropin- (HCG-) induced behavioral receptivity, suggesting that endogenous prostaglandin synthesis may have a role in regulating female sexual behavior. Flurbiprofen blockade of HCG-induced receptivity was reversed by PGE2 administration, suggesting that FBP's effects are PG synthesis-specific.