Idiopathic pulmonary fibrosis (IPF) is a relentlessly progressive disease with inadequate response to conventional treatment with corticosteroids and/or immunosuppressive agents in most patients. Interferon-gamma (IFN-gamma), an antifibrotic agent, has been proposed as a novel therapeutic approach. Several investigators have shown a relative decrease in systemic and pulmonary IFN-gamma activity in patients with IPF. Experimental evidence from animal and human studies also suggests that IFN-gamma administration may ameliorate lung fibrosis. Clinical experience is, however, limited to a single clinical trial that showed objective functional improvement in a small number of patients treated with IFN-gamma and low-dose corticosteroids. Further research is needed to characterise the efficacy, safety and optimum route of administration of this agent before it can be recommended for use in routine clinical practice.