Cryptococcus neoformans commonly causes opportunistic infections in immunocompromised patients, especially in patients with AIDS. CD4+ T-lymphocytopenia in AIDS indicates an increased risk of opportunistic infection and a decline in immunological function. Idiopathic CD4 T-lymphocytopenia (ICL) is characterized by depletions in the CD4+ T-cell subsets, without evidence of HIV infection. Immunodeficiency can exist in the absence of laboratory evidence of HIV infection, and T-cell subsets should be evaluated in patients who present with unusual opportunistic infections. We report a case of pulmonary cryptococcosis and lung cancer in a patient with persistently low CD4+ cell counts, without evidence of HIV infection.