1. Phosphate solution, prostaglandin F2alpha and E2 , arachidonic acid and arginine vasotocin were injected intrauterinely or intravenously into laying quail hens 6 h before expected oviposition. Following injections, induced ovipositions and secretions of pigment from their shell glands were observed. 2. The effects of intrauterine injection with prostaglandins, which induced oviposition and pigment secretion, were not inhibited by pre-injection of indomethacin. 3. Indomethacin completely inhibited the inducing effects on oviposition and pigment secretion of intrauterine injections with phosphate solution and arachidonic acid. 4. Intravenous injection with arginine vasotocin or prostaglandins also induced oviposition and pigment secretion; indomethacin, however, only inhibited pigment secretion. 5. It is concluded that the effects of prostaglandins on pigment secretion from the shell gland were demonstrated experimentally.