Nontuberculous mycobacteria (NTM) are widely present in the environment, although they rarely cause infection in humans. However, infection by NTM has been increasingly recognized worldwide in the context of the human immunodeficiency virus (HIV) epidemic and therapeutic immunosuppression. Mycobacterium kansasii is a slow-growing photochromogenic mycobacterium, which mainly causes pulmonary infection in patients with predisposing lung diseases, and, occasionally, disseminated infection with poor outcomes in immunocompromised patients. We report on the first case of lymphadenitis caused by infection with M.kansasii in an HIV-infected patient in Korea. The patient showed significant improvement after receiving antituberculous therapy (isoniazid, rifabutin) in combination with surgical drainage and highly active antiretroviral therapy (abacavir, lamivudine, and lopinavir/ritonavir).