The biosynthesis of uteroglobin in three regions of the rabbit oviduct was assessed by means of immunocytochemical studies, radioimmunoassay measurements of the protein, and quantitative determinations of its mRNA. Immunocytochemical observations suggested that the number of immunopositive cells and the intensity of their immunolabelling were similar in the distal (infundibular) and the middle regions. In contrast, the isthmic portion appeared to contain less positive cells and weaker immunolabelling. In agreement with these findings, biochemical studies demonstrated that the tissue contents of uteroglobin and its mRNA were similar in the distal and the middle regions whereas the concentrations of both were about three-to four-fold lower in the isthmic portion. The results are discussed in relation to a possible role for uteroglobin in maintaining appropriate environmental conditions for the gametes and the early embryo.