Clusterin or sulphated glycoprotein-2 is a major component of the rete testis fluid, synthesized by the rete testis epithelial cells and Sertoli cells. Differences in the two-dimensional polyacrylamide gel electrophoresis pattern of clusterin-like proteins have been reported in rete testis fluid from Booroola rams carrying the fecundity gene FecB, when compared with that from non-carrier rams. In order to determine whether the FecB gene influences the expression of the clusterin gene, we used a rat clusterin cRNA probe to investigate mRNA species in the tissues of homozygous (BB) or non-carrier (+ +) Booroola sheep. Northern blots of polyadenylated RNA showed hybridization to the cRNA probe in the testis, ovarian follicles, corpora lutea and stroma, pituitary and liver. A major mRNA transcript was observed at 2·3 kb and a minor transcript in some tissues at 0·8 kb. Densitometry of the autoradiographs revealed no FecB-specific differences in the densities of the hybridization signals from + + and BB testis or ovarian follicle, corpora lutea or stromal RNA. We conclude that the gene for ovine clusterin is expressed widely in the tissues of sheep and that its expression is not affected by the presence of the FecB gene.