We describe an 8-year-old boy with CVID and chronic CMV infection. Although at onset he was diagnosed as IgA deficiency, 4 years after his clinical manifestations because compatible to CVID. During his clinical course he had suffered from various disorders as follows; AIHA, interstitial pneumonia, hemophagocytic syndrome, chronic gastroenterocolitis and so forth. At the age of 8 the PCR of CMV-DNA of biopsy specimen from colon, lung and bone marrow were confirmed to be positive. Hematological examinations revealed abnormal cellular immunity such as decreased CD 4/8 ratio with increased HLA- DR+ CD 8+ T cell, decrease of absolute blood lymphocytes count and reduced response of lymphocytes to blastogenetic agents. These findings brought us to diagnose him as having CVID complicated with chronic CMV infection. This case gives us some impact to speculate what role CMV infection plays in CVID, Whose etiology is unknown.