Parvovirus B19 has been identified as the etiological agent of "fifth disease" in childhood. It is also a rarely reported cause of anemia in transplanted patients. During a period of 18 months we observed four cases (2 male and 2 female; 53 +/- 4.24 years) of severe aplastic anemia due to parvovirus B19 in kidney transplant patients. The overall incidence of the disease was 6.3% of all our transplanted patients. Symptoms of the disease occurred 22.5 +/- 9.75 days post-operatively. Serum creatinine was 1.5 +/- 0.35 mg/dl. Hb was 6.58 +/- 0.6 g/dl. All patients recovered with 15 days of high doses of commercial immunoglobulins. We conclude that B19 parvovirus infection is probably an underestimated disease in transplant patients. It is a first-period infection, probably donor-transmitted. High dose immunoglobulins are an effective but costly therapy.