We report the first case of acute kidney injury related to intravenous zoledronic acid (ZA)in a patient with multiple myeloma in Japan. A 37-year-old male was diagnosed as having multiple myeloma (MM) of the Bence Jones lambda type. He showed a good response to two courses of vincristine, adriamycin and dexamethasone (VAD) therapy, and remarkable reduction was seen in plasma cells in bone marrow from 38.4% to 6.8% and 24-hour urine protein from 18.5 g/dL to 2.8 g/dL. At that time, serum Cr(s-Cr) of 0.7 mg/dL and calcium of 9.3 mg/dL were in the normal range. ZA was administered intravenously at the dose of 4 mg for the first time. Subsequently, he developed a fever of up to 39.4 degrees C and used NSAIDs and cefepime. Four days later, s-Cr increasd rapidly to 7.3 mg/ dL and he received hemodialysis (HD) therapy. Four weeks later, renal biopsy was performed and demonstrated cast nephropathy (CN) and acute tubular necrosis. Seven months later, renal function had improved. ZA may be an identifiable precipitating factor of CN. We recommend that ZA should be used with caution, especially hypovolemia and NSAIDs, in patients with MM and renal insufficiency.