<p>Thymoma is associated with various immunological abnormalities, most notably Good syndrome; however, the full spectrum of immune dysfunction in these patients remains unclear. To evaluate the clinical and immunological characteristics of patients with thymoma and to identify occult immunodeficiency as well as associated autoimmune, infectious, and allergic conditions. In this retrospective single-center study, 37 adult patients with thymoma who had undergone thymectomy were evaluated at least one year after surgery. Clinical data, autoimmune and allergic comorbidities, infection history, and immunological parameters including immunoglobulin levels and lymphocyte subsets were analyzed. Good syndrome was identified in 2 patients (5.4%). However, additional immunological abnormalities were observed, including NK cell deficiency (16.2%), B cell lymphopenia (5.4%), isolated IgM deficiency (5.4%), and IgG subclass deficiency in 1 patient (2.7%). Recurrent infections were reported in 67.6% of patients. Autoimmune diseases were present in 86% and allergic diseases in 43.2% of patients. Patients with immunological abnormalities tended to have a higher frequency of recurrent infections. Our findings suggest that immune dysfunction in patients with thymoma may extend beyond classical Good syndrome and may involve a broader spectrum of immunological abnormalities. Systematic and long-term immunological evaluation may be important for the early detection and management of these conditions.</p>