ABSTRACT: Persistent infertility after apparently successful vasectomy reversal is common. One possible etiology is epididymal epithelial dysfunction resulting in improper sperm maturation after vasectomy reversal. The epididymal epithelium secretes a number of proteins that are thought to be required for the maturation of sperm. Ligation of the vas deferens during vasectomy may affect the synthesis of some of these proteins. In the present study, the function of the epididymal epithelium was assessed at early times after vasectomy (1, 4, and 7 days) by measuring the level of mRNA of 4 secreted proteins: Crisp-1, clusterin, osteopontin, and transferrin. In addition, the site of synthesis of these proteins was determined by immunocytochemistry. The results demonstrated that the expression of Crisp-1 and clusterin, representative epididymal secretory proteins, was largely unaffected by vasectomy. However, osteopontin mRNA increased in the vas deferens in response to vasectomy. Immunocytochemical localization of osteopontin suggested that both infiltrating immune cells and deferential luminal epithelium were responsible for this up-regulation. Transferrin expression was viewed as a marker for immune cells at the site of injury. However, both the caput epididymis and deferential epithelia were found to express transferrin, in addition to immune cells. In conclusion, there appear to be only minor changes in expression of genes encoding epididymal secretory proteins acutely after vasectomy, but, not surprisingly, there was evidence of an inflammatory response after vasectomy.