In the past few years, advances in molecular and cellular immunology have greatly enhanced our understanding of the immunopathogenesis of tubulointerstitial nephritis and vasculitis. This review focuses on recent observations regarding nephritogenic tubulointerstitial antigens, their expression and presentation by tubular epithelial cells, the subsequent immune response, and the factors that serve to modulate this response. The latter part of this review summarizes recent findings regarding the role of autoantibodies in the immunopathogenesis of vasculitis.