BACKGROUND: Tubulointerstitial nephritis (TIN) is typically seen in association with drug exposure and infection or in autoimmune diseases such as Sjogren's syndrome or systemic lupus erythematosis. The recently described IgG4-related systemic diseases can affect many organ systems including the kidney and typically respond to corticosteroid treatment. CASE: We present a case of IgG4-related TIN in a patient with concomitant chronic lymphocytic leukemia. To our knowledge, IgG4-related TIN has not been associated with any hematological disorder such as chronic lymphocytic leukemia.
 CONCLUSION: We propose that all kidney biopsies with significant plasma cell infiltrate should be stained for IgG4 as response to treatment is common.