Parvovirus B19 causes persistent erythroid aplasia in immunocompromised hosts. From April through July 1996, we encountered five adult patients presenting with reticulocytopenia and fever caused by parvovirus B19 infection. The reticulocyte count of four patients with normal immunity recovered within two weeks after the onset of fever. However, in the one remaining patient with common variable immunodeficiency (CVI), reticulocytopenia, and other symptoms including fever and the elevation of lactate dehydrogenase (LDH) levels persisted beyond 16 days of onset. Although the DNA of parvovirus B19 was detected in the peripheral blood of the CVI patient, neither immunoglobulin Ig-G nor Ig-M antibodies specific to the virus were detectable. We administered 50 mg/kg of Ig to the CVI patient for six days. The reticulocyte count recovered promptly on the sixth day of the treatment and parvovirus B19 DNA was not detectable 30 days after therapy. This indicates that although patients with CVI may be susceptible to persistent erythroid aplasia during an endemic of parvovirus B19, the complication can be treated successfully with relatively low-dose Ig.