Good's syndrome is an association of thymoma and immunodeficiency. The symptoms are recurrent sinopulmonary infections in addition to the compressive side of thymoma. A laboratory finding is notable for the absence or decrease of B lymphocytes, hypogammaglobulinemia, inversion ratio CD4/CD8 and abnormal proliferative response to mitogens.Female, 49-year-old started five months earlier with lower limb edema, postprandial vomiting, dysphagia, chronic diarrhea and weight loss. A second endoscopy ruled gastric neoplasia. Chest radiography with mediastinal widening, Thoraco-abdominal CT with bilateral pleural effusion and a mass in the anterior mediastinum, histopathological report of the tumor: B1 thymoma. Laboratory findings: IgG 349 mg/dL, IgA 70.3 mg/dL, 37.1 IgM mg/dL, Ca125 631 UI/mL, leukocytes 7890 mm3, hemoglobin 13.2 g/dL, lymphocytes 2060 mm3, CD16+CD56+ 122 cells/µL, CD19 77 cells/µL, CD3 2052 cells/µL, CD4 977 cells/µL, CD8 998 cells/µL; ratio CD4/CD8 0.98, hepatitis C, B and HIV negative. They requested valuation to Clinical Immunology and Allergy due to hypogammaglobulinemia, the diagnosis of Good's syndrome was confirmed and initiated with intravenous gamma globulin replacement to immunomodulatory dose of 1 g/kg, she reached replacement goal in the third dose of immunoglobulin intravenous, with clinical improvement. She died four months later from cardiac complications.Despite the variability of presentation, Good's syndrome should be suspected as part of the paraneoplastic manifestations of thymoma.