The authors have used three laying and three non-laying muscovy ducks (Cairina moschata, Linneaus, 1758), in order to study morphological and histochemical aspects of the luminal oviductal epithelium. The results showed that the oviduct of the muscovy duck is well-developed at the left side, atrophied at the right side and consists of six different regions: fimbria, infundibulum, magnum, isthmus, shell-gland and vagina. The oviduct is more evident and developed in the laying phase of the reproductive period. The lining epithelium is of single cylindric ciliated type, with the exception of the region of the vagina, where it is of pseudo-stratified cylindric ciliated type. In all portions of the oviduct it was observed that the epithelium presents ciliated and non-ciliated cells. It was verified a predominance of non-ciliated cells in the laying period and of ciliated cells in the nonlaying period, with the exception of the regions of the fimbriae and shell-gland, where an equilibrium of these two cell-types is observed. With regard to the detection of mucous substances, it was noted that the surface oviductal epithelium showed positive reactivity to PAS in the infundibulum, magnum and isthmus, and to A.B. pH 2.5 and 0.5 in the infundibulum, magnum, isthmus (with the exception of the laying period) and vagina. It was not observed the presence of mucous cells in the fimbriae and shell-gland in both phases of the reproductive period