Background. Serious infections constitute a major problem for patients with cancer, and new approaches must be found in dealing with these. The pathophysiology of neutropenic infection is not well understood, although there is some evidence that, as in sepsis in the primarily immunocompetent host, a pro-and an antiinflammatory phase can be discriminated. In the recent literature is described a series of nonneutropenic patients with sepsis in whom interferon-␥ was successfully administered during the immunoparalytic phase, a concept that might possibly be extended to immunocompromised hosts. Procedure. A 14-year-old patient with RAEB-T/hypoplastic M2 and chemotherapy-induced neutropenia developed a severe infection and continued to deteriorate clinically despite maximum supportive measures, including broad antibacterial and antifungal coverage. On the basis of monocyte de-activation this patient was considered to be in the immunoparalytic phase of sepsis and consequently treated with 60 µg/m 2 of interferon-␥ per day for 10 days. Results. The patient made a rapid clinical recovery, and biochemical markers of infection improved promptly. At the same time, the fraction of activated monocytes normalized rapidly and stably. We hypothesize that treatment with interferon-␥ effected this rapid restoral of monocyte activation and that monocyte reactivation might have contributed to the patient's prompt recovery from his severe infection. Interferon-␥ treatment was well tolerated. Conclusions. Immunostimulation with interferon-␥ might prove to be a valuable adjuvant treatment for patients with chemotherapyinduced neutropenia during the rare scenario of infection with immunoparalysis.