Good's syndrome is an immunodeficiency disease involving thymoma accompanied by hypogammaglobulinemia. We encountered a case of Good's syndrome accompanied by agranulocytosis that followed a rapid clinical course. A 72-year-old man visited our hospital with a two-week history of a sore throat. Candida albicans was detected in the pharynx, and hypogammaglobulinemia was detected in addition to granulocytopenia. The patient subsequently developed septic shock and followed a rapid clinical course which ended in death. Good's syndrome with agranulocytosis was diagnosed at autopsy. Good's syndrome accompanied by agranulocytosis can follow a rapid clinical course and some cases remain asymptomatic until old age. Its prompt treatment is crucial.