Good's syndrome is a rare adult-onset immunodeficiency disease characterized by hypogammaglobulinemia and thymoma. A 61-year-old male patient was diagnosed with Good's syndrome after a 2-year history of recurrent respiratory infections. Chest X-ray and chest computed tomography scan showed a mediastinal mass which was surgically removed. Histology revealed a thymoma. Following surgery he presented with recurrent respiratory and urinary tract infections and with esophageal candidiasis, even though his overall conditions dramatically improved after starting treatment with an appropriate dosage of intravenous immunoglobulins. Laboratory tests showed hypogammaglobulinemia, mild neutropenia, lymphopenia with no B cells, decreased CD4+ lymphocytes with an inverted CD4/CD8 ratio and increased interleukin-4-producing CD4+ lymphocytes, suggestive of an excessive Th2 response.