A 73-year-old woman was presented with altered mental status and disorientation. She was diabetic and hypertensive, and she had experienced an ischemic cerebrovascular accident 3 years ago. Physical examination revealed the findings of chronic obstructive pulmonary disease, cor pulmonale and congestive heart failure. Hepatomegaly, splenomegaly and ascites were found and might be associated with postsinusoidal portal hypertension secondary to congestive heart failure. Laboratory tests showed uremia, lymphocytosis and thrombocytopenia. Neurologic findings were related with uremia and hypoxia. Multiple pathologic lymphadenopathies were seen in abdominal ultrasonography and thoracic computed tomography. Bone marrow histology indicated chronic lymphocytic leukaemia (CLL). The reason for acute renal failure was leukaemic infiltration of the kidneys due to CLL that was shown with renal biopsy. Blood urea nitrogen (BUN) and serum creatinine responded well to cyclophosphamide and methyl prednisolone treatment. In CLL, direct renal involvement is frequently seen in autopsy studies especially in advanced disease, however, renal failure due to leukaemic infiltration is extremely rare.