Cat-scratch disease is usually a benign, self-limited disease. Infection may be asymptomatic but is commonly associated with painful regional lymphadenitis. Occasionally, disease may result in systemic symptoms and dissemination. Five adult patients, aged 24 to 57 years, were diagnosed as having cat-scratch disease, based on a positive history of cat scratches followed by typical symptoms including painful regional lymphadenitis, malaise, and positive cat-scratch skin tests. Diagnostic evaluations revealed no other cause for the lymphadenitis. Three patients had not received prior treatment with antibiotics, and two patients had failed to improve on other antibiotics. All five were treated with oral ciprofloxacin, 500 mg by mouth, twice daily. All patients had dramatic improvement in symptoms within a few days and none has relapsed during follow-up. This is the first report of successful treatment of cat-scratch disease with ciprofloxacin, which appears to be an effective therapy for cat-scratch disease in adults.