Thymoma has been associated with both humoral immunodeficiency and cellular immunodeficiency, but the latter association has never been described in the pediatric age group. We report a 15-year-old female with thymoma, recalcitrant oropharyngeal candidiasis, recurrent generalized cutaneous herpes simplex virus type 2 infection, recurrent pneumonia and myasthenia gravis. Pathology of the thymic lesion showed a 10times5x6 cm extensively hyalinized mass with residual regions of spindle cell predominant and lymphocyte-rich thymoma. There was no evidence of humoral immunodeficiency but there was clinical and laboratory evidence of cellular immunodeficiency with cutaneous anergy and absence of T cell proliferation to Candida antigen. Six weeks after the thymoma was resected, she was no longer anergic and Candida proliferation was normal, although she continued to experience infections. This is the first reported pediatric patient with an association of cellular immunodeficiency with thymoma.