A 55-year-old white man with a history of hypertension, fibromyalgia, and colonic polyps presented with unrelenting plantar warts on his hands and feet for the past 4 years. He was otherwise healthy and without a history of recurrent infections. Physical examination was unremarkable except for extensive warts on his hands and feet. Pertinent laboratory findings included hypoalbuminemia, hypogammaglobulinemia, and lymphopenia most severely affecting CD4(+) T cells. Testing for HIV infection was negative. This clinical and laboratory presentation suggested a combined humoral and cellular immunodeficiency syndrome that could be best explained by loss of lymphocytes, immunoglobulins, and other serum proteins. Additional immunologic testing revealed a marked reduction in peripheral blood naive (CD4(+)CD45RA(+)) T cells. A 24-hour stool collection showed a markedly elevated alpha(1)-antitrypsin level. These findings were most consistent with the diagnosis of intestinal lymphangiectasia, a type of protein-losing enteropathy associated with hypoalbuminemia, hypogammaglobulinemia, and lymphopenia, characterized by a preferential loss of naive CD4(+) T cells into the gastrointestinal tract. This case illustrates the importance of considering intestinal loss of immunoglobulins and lymphocytes in the differential diagnosis of the adult patient who presents with laboratory evidence of a combined humoral and cellular immunodeficiency. It also underscores the diagnostic utility of the clinical immunology laboratory and how flow cytometry, in particular, can contribute to an understanding of pathogenic mechanisms.