This study was undertaken to obtain additional information about the incidence and characteristics of fetal parvovirus B19 infection in an unselected autopsy series, and to assess the distribution and quantitation of inclusions in various organs. Autopsy records from 673 fetal and neonatal autopsies performed at Women and Infants' Hospital during 1985 through 1990 were reviewed. Thirty-two cases of hydrops fetalis were identified, and, of these, 5 had parvovirus infection. This gives an incidence of fetal parvovirus infection resulting in hydrops fetalis of 0.7% among all autopsies, and a 16% incidence among cases of hydrops. Thirty-five percent of the cases of hydrops had malformations; a muscular ventricular septal defect was noted in one of the 5 cases of parvovirus infection. All 5 parvovirus cases had characteristic erythroid nuclear inclusions, and these inclusions were resistant to tissue degenerative changes. The most reliable tissue for histologic diagnosis was the liver, followed by heart and lung. Only 2 of 5 placentas had diagnostic inclusions, making examination of the placenta alone insufficient for ruling out fetal parvovirus infection.