Parvovirus B19 infection can cause severe complications in pregnant women, individuals with haemolytic anaemia, and those who are immunocompromised. In a hospital outbreak of this infection, a balance should be struck between protection of these individuals and the maintenance of medical services. The index case of an outbreak of parvovirus B19 infection among staff and patients of a paediatric ward was not identified. 58 members of staff were screened for B19 markers and 4 of the 6 susceptible men and 6 of the 24 susceptible women became infected (p = 0.05) as defined by serum IgM and viraemia. 1 of the 11 adults (10 members of staff and 1 parent) infected remained symptom-free. 12 immunocompromised patients were also assessed, and symptom-free infection developed in 2 of these. During the outbreak staff with symptoms were put on sick leave, immunocompromised patients (there were none with haemolytic anaemia) were given normal human immunoglobulin and nursed in single rooms by B19 IgG-positive, IgM-negative staff, and the ward was closed to B19 IgG-negative pregnant women. However, the limitation of spread of infection cannot be attributed with certainty to the measures taken.