A disease condition with clinical and pathologic findings compatible with psittacine proventricular dilatation disease was diagnosed in a canary (Serinus canaria), a greenfinch (Carduelis chloris), a long-wattled umbrellabird (Cephalopterus penduliger), and a bearded barbet (Lybius dubius). The canary and the greenfinch were kept as pets by different owners, whereas the bearded barbet and the long-wattled umbrellabird were kept in separate mixed species enclosures at the Barcelona Zoo. Clinical signs were variable in all 4 birds and included polyphagia, weight loss, weakness, and ataxia. Postmortem examination findings were also variable and included emaciation, hepatic and renal atrophy or enlargement, gallbladder dilatation, and intestinal and ventricular dilatation. Histopathologic lesions in all birds consisted of multifocal lymphoplasmacytic infiltration of myenteric and cardiac nerves and ganglia. These lesions are characteristic of proventricular dilatation disease of psittacine birds.