We report a case of a 31-year-old woman with common variable immunodeficiency (CVID) complicated with intractable diarrhea and the functional disorder of renal tubules. The patient became hypogammaglobulinemic after she suffered from measles at 6 years of age. She also suffered from lupus-like syndrome at 7 years of age. The complete remission was obtained by glucocorticosteroid treatment. An intravenous immunoglobulin replacement therapy was introduced at 11 years of age, since then her general condition was stable for more than 20 years. When she was 29 years old, she suffered from generalized malaise, anorexia with body weight loss, and numbness of face. The intractable diarrhea as protein loosing syndrome, and the severe abnormality of electrolyte balance with metabolic acidosis as the functional disorder of renal tubules were found. Her condition was not improved by the electrolytes or alkali replacement therapy. She was admitted for further evaluation and treatment. The intractable diarrhea and the functional disorder of renal tubules were dramatically improved after absolute restriction of food intake under hyperalimentation. When she began to take food, the symptom and sign became worse again. The interstitial nephritis and nonspecific inflammation of intestine were found by the tissue biopsy. The most characteristic finding was the infiltration of lymphocytes (predominantly CD 8 + T lymphocytes) in both intestinal mucosa and renal interstitium. The introduction of glucocorticosteroids improved her general condition and biochemical findings. This CVID case is complicated with intractable diarrhea and the functional disorder of renal tubules which is associated with the infiltration of CD 8 + lymphocytes in intestine and kidney. We consider that such case is very rare and valuable to report.