A male patient aged 67 years with chronic renal failure (CRF), who had undergone hemodialysis since June 3, complained of dyspnea while walking on June 23, 1998. Rapidly progressive anemia and severe reticulocytopenia were noted. Serological tests showed that parvovirus B19- (B19) specific IgM antibody, but not IgG antibody, was present in the patient's serum. B19 DNA was detected in the patient's serum by the polymerase chain reaction (PCR). Therefore, a definite diagnosis of transient aplastic crisis induced by B19 was made. On June 10, prior to the appearance of this case, a female nurse aged 27 years working in our hemodialysis center, complained of cough, fever and arthralgia. Another female nurse, aged 35 years, developed similar symptoms on July 3. Both nurses had a positive IgM titer against B19, but were negative for IgG, indicating an acute B19 infection. These findings led us to suspect that this series of B19 infection was spread by nosocomial transmission. Although some cases of B19 infection have been reported to occur in laboratory staffs, the B19 nosocomial infection has not been described in the literature. We also suggest that a transient aplastic crisis due to B19 infection could lead to severe anemia in cases of CRF whose erythropoiesis is maintained by a recombinant human erythropoietin.