Changes in gizzard motility were studied with a particular reference to egg laying by a radiotelemetric measurement of electrical activity of the thick caudodorsal muscle of the gizzard in the chicken. There was a clear diurnal pattern in gizzard motility. Superimposed on this diurnal pattern, gizzard motility declined shortly before oviposition followed by an immediate increase after oviposition. Although fasting reduced mean frequencies of gizzard motility on an hourly or daily basis, a marked increase still occurred soon after oviposition. These results suggest that gizzard motility is not only influenced by food availability but also is affected by the hen's laying behavior.