Background: The actual prevalence of gastrointestinal diseases in primary immunodeficiency in adults is not defined and whether these patients were purely primary – immunodeficient is not known, but the strong association between these two nosology has been demonstrated. Chronic intractable diarrhea in adults can suggest common variable immunodeficiency which is characterized by a host of gastrointestinal lesions that can mimic lymphocytic colitis or other conditions. Methods: We analyzed 7 adult patients with chronic diarrhea apparent intractable, for which it was finally established Common variable immunodeficiency, based on significant reductions in the immunoglobulins we assigned the diagnosis of common variable immunodeficiency. Colonoscopy and upper GI endoscopy with biopsy were performed. Results: There were 3 males and 4 females, age at diagnosis ranged from 16 to 42 years. They were suffering from refractory diarrhea unknown etiology for the duration from 3 to 6 years. There were 13.5 episodes of hospital admission during this period. On average, a patient was hospitalized for median 21.3 ± 5.6 days. The main causes of hospitalizations was: prolonged diarrhea with malabsorption, fever, pneumonia. Gastrointestinal patterns in these patients was: the stomachs of 4 of patients showed lymphoid aggregates, 3 patients had a lymphocytic gastritis pattern; helicobacter pylori were found in 3 patients, in one patients was identified gastric MALT-lymphoma. Biopsy for colon showed that 4 patients had a lymphocytic colitis pattern and 2 patients had a pattern for ulcerative colitis. Conclusion: In any patient suffering from chronic refractory diarrhea unrelated to known causes, could have common variable primary immunodeficiency with clinical manifestations in different periods of life. Lymphocytic colitis or ulcerative colitis can be suspected in patients with primary immunodeficiency.