We describe a 65-year-old female who presented with arthritis involving the small joints of her hand, wrists, and knee, fever, rash, and leukocytosis. During the course of her illness, she developed elevated transaminases, myositis, bilateral pleural effusions, a large pericardial effusion compressing the right atrium, and cardiomyopathy with impaired left ventricular function. The patient had evidence of acute parvovirus B19 infection by serology, although parvovirus specific DNA sequences from peripheral white blood cells were negative by polymerase chain reaction. This illness raised concern about possible collagen vascular disease. Low titers of antinuclear antibodies were present transiently, and other autoantibodies were undetected. Treatment with intravenous immunoglobulin resulted in dramatic resolution of her disease manifestations. Pericardial effusion and cardiomyopathy may be rare sequelae of parvovirus B19 infection. The apparent improvement with intravenous immunoglobulin could have been related to clearance of infection or down regulation of host immune response.