Psittacine neuropathic gastric dilatation was studied in four cockatoos (Cacatua spp.). The birds died with characteristic clinical signs, and post-mortem examination revealed a highly distended proventriculus. Upon light microscopic examination, most of the ganglia of the gastric plexus and some of the duodenal myenteric plexus appeared destroyed and replaced by round cell accumulations; the same was true for the celiac ganglion. The neuronal perikaryon of the celiac ganglion and the myenteric plexus revealed intranuclear and extranuclear eosinophilic inclusion bodies. The electron microscope revealed virus-like particles outside and within those inclusions. These particles were similar to particles described and identified as paramyxovirus.