B19 fetal infection has been associated with hydrops or fetal death. We report four cases of meconium peritonitis in hydropic fetuses with laboratory diagnosis of B19 infection. Parvovirus B19 DNA was detected by in situ hybridization both in cord blood and in amniotic cells in three fetuses, while in one case only cord blood was available and proved positive. Signs of active or recent B19 infection in maternal serum samples were documented only in two cases, which proved positive for specific IgM antibodies anti-B19. Maternal B19 infections were asymptomatic and fetal anomalies were observed during a routine ultrasound scan. A common feature of the hydropic fetuses was the presence of abdominal ascites concomitant with or preceding alterations, suggesting meconium peritonitis. The four pregnancies had a preterm outcome: in two cases infants recovered following surgical treatment, in one case spontaneously, and the other one was stillborn. Since vascular inflammation has been documented in B19 infection and congenital bowel obstruction results from vascular damage during fetal life, our observation suggests the need for investigating B19 infection in the presence of meconium peritonitis for a better understanding of the pathogenetic potential of B19 parvovirus in intra-uterine infection.