Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world and is characterized by a progressive accumulation of functionally incompetent monoclonal lymphocytes. Renal involvement has been described in CLL but is uncommon. Granulomatous interstitial nephritis is a rare but characteristic hallmark of certain diseases such as sarcoidosis and tuberculosis. These epithelial reactions have also been reported with medications, infections, inflammation, Wegener's granulomatosis, and jejunoileal bypass. We present a 74-year-old woman with a stage 0 chronic lymphocytic leukemia who developed acute renal failure following the initiation of alendronate. The renal biopsy revealed an acute granulomatous interstitial nephritis. Infectious and inflammatory etiologies were ruled out. Hemodialysis was required despite discontinuation of all medications. Partial recovery of renal function occurred after 6 weeks of prednisone therapy and cyclophosphamide. This report describes a unique case of acute granulomatous interstitial nephritis and leukemic cell kidney infiltration by CLL.