A 16-year old boy with an early history of recurrent lower respiratory tract infections exhibited symptoms of prolonged septic fever and liver abscess. Cultures from liver puncture were positive for Staphylococcus aureus, and the patient initially responded to antibacterial therapy. After a period of 4 months, however, the infection relapsed, and further treatment with broad antibacterial, antifungal and tuberculostatic drugs was ineffective. Neither soluble nor particulate stimuli were found to elicit the respiratory burst response in granulocytes from the patient. Spectral analysis of granulocyte cytochrome-b confirmed the diagnosis of chronic granulomatous disease. Since the patient's physical condition deteriorated severely during the prolonged (10-week) septic course, immunosupportive interferon-gamma was added to the anti-microbial therapy. With this regime, the fever subsided and the general condition of the patient improved dramatically. He could be discharged from hospital 9 weeks after the introduction of interferon-gamma and was, at an elective follow-up control 1 month later, convalescing and showed no signs of active infection.