A 62-year-old male was sent to the emergency room due to a high fever and generalized skin rash after taking allopurinol for 9 days. Physical examination was normal except for the generalized skin rash presenting with erythematous macules. Complete blood count showed leukocytosis with eosinophilia. Blood biochemistry showed impaired renal and hepatic function. Pathologic examination concluded that the skin rash was erythema multiforme. These findings met the diagnostic criteria for allopurinol-induced hypersensitivity syndrome (AHS). Our patient not only had the most common skin lesion but soon developed acute renal failure that required intermittent hemodialysis, despite rapid discontinuation of allopurinol and adequate hydration and steroid therapy. No other causes of acute renal failure were found. Renal impairment was the worst part of the patient's condition and he never completely recovered. AHS should be considered in the differential diagnosis of acute renal and hepatic failure in patients with evidence of allergy and recent use of allopurinol.