During 1987 and 1988, we identified 9 adults at the Medical and Rheumatology Services of the University of Iowa Hospitals and Clinics who had a clinical diagnosis of fifth disease; 8 of the 9 had symptoms of joint involvement. Another 12 adults with serologic positivity for anti-parvovirus B19 IgM antibody presented with polyarthralgia/polyarthritis. Patients were usually found to be seronegative for rheumatoid factor, and none developed nodules or erosive disease. Many patients with chronic disease met criteria for a diagnosis of rheumatoid arthritis. A diagnosis of parvovirus B19 infection should be considered during the initial visit of patients with polyarthralgia/polyarthritis.