Twin pregnancies complicated by infection due to parvovirus B19 are uncommon. We report a case in which only one fetus developed a symptomatic infection, which presented at first as ascites and pleural effusion; later, meconium peritonitis developed. Hydrops spontaneously resolved, and at birth meconium peritonitis was successfully treated with surgery. However, even with the positive outcome of this pregnancy, a long-term follow-up is needed to exclude damage other than injury to the erythropoietic system.