Abstract Backgrounds: Mutations in DNA-binding domains of STAT1 lead to delayed STAT1 dephosphorylation and afterwards gain-of-function. The clinical phenotype is broad and can include chronic mucocutaneous candidiasis and/or combined immunodeficiency. Objectives: We report a case of 7-year old female patient. She had recurrent pneumonia since infancy and she was hospitalized several times. She had persistant lymphopenia with normal immunoglobulin levels and lymphocyte subsets. Findings: STAT1 mutation was defined by next generation Sequencing PID panel. Despite the antifungal therapy, oxygen requirement continued, methylprednisolone and Janus-associated kinase (JAK) inhibitor (ruxolitinib) was started as therapy. Immunodysregulatory features of disease improved after Janus kinase inhibitor treatment. Conclusion: In patients with STAT1 GOF defect, ruxolitinib treatment may be effective for interstitial lung disease if hematopoietic stem cell transplantation can not be performed.