C J H P – Vol. 55, No. 2 – April 2002 J C P H – Vol. 55, n 2 – avril 2002 Acute interstitial nephritis is a disease affecting the renal tubules and interstitium. It is thought to occur secondary to an allergic hypersensitivity reaction. The clinical presentation is variable and nonspecific, and may include fever, maculopapular rash, arthralgia, edema, hypertension, eosinophilia, eosinophiluria, pyuria, hematuria, proteinuria, oliguria, leukocytosis, elevation of serum immunoglobulin E, hyperkalemia, and acidosis. Acute interstitial nephritis can have an infectious, inflammatory, or drug-related cause. Numerous drugs have been implicated in acute interstitial nephritis, some of which include nonsteroidal anti-inflammatory drugs, diuretics, anticonvulsants, allopurinol, and antibiotics. Fluoroquinolones are commonly used antibiotics that are thought to be relatively nontoxic. However, the potential exists for these agents to cause substantial morbidity, as illustrated by published reports of fluoroquinoloneinduced acute interstitial nephritis. Ciprofloxacin accounts for the majority of these cases, with just a few reports for norfloxacin. A MEDLINE search for January 1966 to December 2001 yielded only one published report of acute interstitial nephritis secondary to levofloxacin, a newer fluoroquinolone. Two cases of fluoroquinolone-induced acute interstitial nephritis are reported here, one due to norfloxacin and the other to levofloxacin. As the use of this class of anti-infectives increases and as new members of the class are introduced, it is important that pharmacists be aware of the growing evidence of this clinically important adverse effect. CASE REPORTS