A method for cannulating the oviduct and uterus of the ewe which permits the continuous volumetric collection of fluid was described. The cannulas remained functional for periods exceeding 50 days without apparent discomfort or harmful effects to the ewe. Three of four ewes continued to exhibit normal es-trous cycles after a cannula was placed in the oviduct. One ewe failed to return to estrus. A uterine horn was cannulated in each of four ewes, and all ewes exhibited at least one es-trous period after the cannula was installed. The volume of fluid secreted by both the oviduct and uterus showed a consistent pattern of variation during the estrous cycle. Fluid volume was low during the luteal phase, increased at the beginning of estrus, reached a maximum the day following onset of estrus and then declined to levels characteristic of the luteal phase. During estrus the volume of fluid obtained from the uterine horn exceeded that obtained from the oviduct, whereas the reverse was true during the luteal phase of the cycle.