Two adult male sheep were used to determine the outflow of protozoa from the reticulo-rumen. The outflow of ciliates was calculated on the basis of their concentration in reticular digesta and volume of effluent leaving the reticulo-rumen. The concentration of ciliates from the genus Entodinium and Diplodinium in reticulum was by 33-63 % and 32-73% lower than in the rumen. The concentration of Holotricha varied between 55.7 and 126.8% of the ruminal density. No differences were found between the concentration of protozoa in reticular digesta taken at the contraction and resting phases of the reticulum. The number of ciliates leaving the reticulo-rumen per day equaled 66-177 % of their number in the rumen, and the apparent residence time of protozoa varied between 13.8 and 36.6 h. It was longest in the case of ciliates from the genus Dipolodinium and the shortest in the case of Isotricha. A technique for the collection of reticular digesta at the contraction and resting phases of the reticulum is described.