We report a patient with Sjögren's syndrome and chronic natural killer lymphocytosis, who developed severe neutropenia, autoimmune hemolytic anemia, and immune thrombocytopenia. High-dose prednisolone therapy improved the hemolytic anemia and thrombocytopenia, but not the CD16(+) CD56(-) NK lymphocytosis completely. Interestingly, indomethacin farnesil (a prodrug of indomethacin) was effective for myalgia and also decreased the number of CD16(+) CD56(-) NK cells. NK lymphocytosis is rarely associated with autoimmune disease, but the combination of indomethacin and steroid therapy may have a favorable effect for such patients.