In severe combined immunodeficiency disease, both T and B cell functions are diminished or absent and affected usually succumb to overwhelming infection within the first year of life. We are reporting a case with severe combined immunodeficiency, Swiss type who suffered from interstitial pneumonia which cleared by treatment with recombinant human interferon gamma. In this case, we don't know the exact mechanism which caused the clearing of the interstitial pneumonia. However, we can speculate that antiviral action and activated macrophages or monocytes, through the recombinant human interferon gamma, might exert its effect on interstitial pneumonia. Though we should extend its application to more cases of SCID with interstitial pneumonia, this report may suggests a new application for interferon-gamma as a potential corrective and therapeutic agent for interstitial pneumonia in congenital immunodeficiency diseases.