The case of a 63-year-old man suffering from the immunodeficiency syndrome developed 12 years after thymectomy due to thymoma is reported. In our patients, the most frequently manifested symptoms resulted from recurrent infections of the upper and lower respiratory tract. In chest X-ray and computed tomography examination, bilateral ground-glass opacities, diffuse areas of infiltrates and bronchiectases are observed. The immunological analysis revealed an almost undetectable level of immunoglobulins in blood plasma and a very low percentage and number of peripheral blood B lymphocytes. The inversion of the CD4/CD8 ratio and the presence of a large population of the CD4 and CD8 double-positive lymphocytes are also observed in peripheral blood. Based on clinical symptoms, Good’s syndrome was diagnosed. This syndrome was observed very rarely in patients after thymectomy and occurred in the course of thymoma.