We describe a case of asymptomatic human parvovirus B19 infection during pregnancy that led to hydrops fetalis and foetal death. The diagnosis was confirmed by the presence of parvovirus B19-specific IgM antibodies in the maternal serum and the pathognomonic findings, which showed intranuclear eosinophilic viral inclusions and margination of chromatin in foetal cells of haemopoietic lineage. Details of clinical, virological, and histological findings are presented. Difficulties in confirming the diagnosis of parvovirus B19 infection in Hong Kong are discussed.