In the present study immunohistochemical staining has shown that the ring fibres of the human spleen contain the major basement membrane components, type IV collagen and laminin. The superiority of immunohistochemical methods in demonstrating basement membrane material in the spleen is emphasized. The results are compared with the demonstration of reticular fibres by Gomori's reticulin stain. The findings provide further information about the relationship between basement membrane material and reticular fibres in human spleen. The nature of splenic ring fibres is discussed in the light of the scientific literature.