Muscovy duck parvovirus (MDPV) has been demonstrated in tissue samples from one- to four-week-old commercially reared Muscovy ducks that were weak, unable to walk and had a high mortality rate. On postmortem examination, the thigh and leg muscles, and the myocardium were found to be pale, and there was a fibrinous exudate on the capsule of the liver, and ascites. The parvovirus was isolated in embryonated Muscovy duck eggs and visualised by negative stain electron microscopy, detected by polymerase chain reaction (PCR) directly from the tissues, and antibodies to it were detected by immunoelectron microscopy, ELISA and immunofluorescence. In addition, the PCR products obtained that represented 1625 bp (74 per cent) of the capsid vP1 gene, including a hypervariable region between Derzsy's disease virus or goose parvovirus and MDPV, were sequenced and shown to be 100 per cent homologous with the MDPV 89384 reference strain, but only 82.3 per cent homologous with Derzsy's disease virus.