Four pregnancies, in two women aged 39 and two women aged 34 years respectively, were complicated by foetal parvovirus B19 infection. First-trimester intrauterine death resulting from multiple congenital anomalies was diagnosed in one patient with proven foetal parvovirus B19 infection. In three patients foetal hydrops was found in the second trimester with variable clinical course. In one of them, foetal hydrops resulted in second-trimester foetal death; in another, foetal hydrops resolved following intrauterine blood transfusion and in a third foetal hydrops resolved spontaneously. Foetal parvovirus B19 infection was diagnosed by polymerase chain reaction (PCR) using foetal cells obtained by amnioscentesis. It is concluded that maternal parvovirus B19 infection is mostly asymptomatic. However, the clinical impact of maternal infection on the foetus is diverse, i.e. infection may result in foetal death or--transient--foetal morbidity, in particular foetal anaemia. In mothers with proven foetal parvovirus B19 infection close monitoring of the foetus by ultrasound is warranted. Occasionally intrauterine transfusion is required. From the literature to date, the estimated incidence of maternal parvovirus B19 infection in pregnancy is 3-7%. The vertical transmission rate approximates 30%. When pregnancy is complicated by foetal hydrops foetal parvovirus B19 infection should be kept in mind.