Objective. To show a possible association between parvovirus B19 infection and the presence of antiphospholipid antibodies (aPL) in patients with rheumatic diseases.Methods. Serum samples obtained from 88 children with various forms of juvenile rheumatic disease and from 40 adults with systemic lupus erythematosus, the antiphospholipid syndrome, or other rheumatic disease, who had previously been tested and shown to be positive for IgG aPL, were analyzed for the presence of B19 DNA, for antibodies against the B19 viral proteins VP1, VP2, and NS1, and for IgG aPL (anticardiolipin, anti- 2 -glycoprotein I, and antiphosphatidylserine). As controls, serum samples obtained from 135 children with noninflammatory bone diseases or growth retardation were also analyzed.Results