Aleutian mink disease (AD) has been characterized by immune complex glomerulonephritis associated with persistent infection of Aleutian mink disease parvovirus (ADV). Histopathological examination of kidneys from ADV-infected mink in this study revealed that interstitial nephritis characterized by prominent damage of renal tubuli and lymphocyte infiltration was also common in AD along with glomerulonephritis. By using strand-specific in situ molecular hybridization technique, replication of ADV was observed in tubular epithelial cells, in addition to epithelial cells of Bowman's capsules and some glomerular cells of the infected mink. Analysis of tubular lesions by a combination of immunohistochemistry and in situ hybridization revealed that the renal tubuli positive for virion DNA or replicative form DNA/mRNA of ADV were also positive for an activation marker of immunocompetent cells, which is shared by B lymphocytes and thymic epithelial cells. Infiltration of a subpopulation of T lymphocytes around infected renal tubuli were observed but deposition of immune complexes in these tubular lesions was not demonstrable. ADV replication in epithelial cells of renal tubuli and cell-mediated immune responses to the infected epithelial cells may play a role in the pathogenesis of interstitial nephritis in Aleutian mink disease.