Prostaglandins (PGs) have been implicated in the mediation of sexual behavior in vertebrates. In this study, the effects of administered PGs on sexual receptivity were examined in the ovariectomized female green anole lizard (Anolis carolinensis). Injection (ip) of 15 microgram PGF2 alpha failed to induce sexual receptivity in nonreceptive females which were either untreated or estrogen primed. On the other hand, PGF2 alpha treatment of sexually receptive estrogen-pretreated females inhibited sexual receptivity 1 h post injection. A dose of 7.5 microgram PGF2 alpha was as effective as 15 microgram in inhibiting sexual receptivity, while a dose of 1.5 microgram was near the minimum effective level. Treatment with 15 microgram PGE2 and, to a lesser extent, PGE1 also reduced sexual receptivity. In contrast, arginine-8-vasotocin, a neuropeptide capable of stimulating smooth muscle contractions in reptiles, did not decrease sexual receptivity. The inhibitory effects of PG treatment observed at 1 h were diminished by 3 h and were no longer present 6 and 24 h post injection, with females, again, being fully receptive. Inhibition of sexual receptivity occurs very rapidly after PGF2 alpha treatment. When tested 5 min post injection, all females treated with 15 microgram arginine-8-vasotocin were sexually receptive. The oviducts were not required for PGF2 alpha inhibition of sexual receptivity, as sexual receptivity was inhibited in oviductectomized females 1 h after the injection of 15 microgram PGF2 alpha. The inhibitory action of PGF2 alpha was also observed when sexually receptive females were injected intracranially rather than ip. Intracranial injection of 3.8 microgram PGF2 alpha inhibited sexual receptivity in females tested 1 h post injection. These results indicate that exogenous PGs, possibly acting centrally within the brain, inhibit sexual receptivity in female A. carolinensis, a species with a rapid mating-induced termination of sexual receptivity.