Proventricular dilatation disease has been recognized as an epornitic of captive psittacines in North America and Europe. PDD is characterized by lymphocytic plasmacytic infiltration of the peripheral and central nervous systems, particularly the myenteric plexuses of the tunica muscularis of the proventriculus and ventriculus. Clinical signs commonly include depression, weight loss, regurgitation, and passage of undigested seeds in the feces. Accompanying central nervous system signs can include ataxia, proprioceptive deficits, seizures, or blindness. However, individual presentations may vary. Gross pathologic findings typically include emaciation, a dilated proventriculus and ventriculus, and thinning of the ventricular wall. While a presumptive diagnosis may be made on clinical signs and gross pathology, definitive diagnosis requires histopathology. The cause and pathogenesis of the disease is as yet unknown, however a viral etiology has been suggested. This paper presents a case of Proventricular Dilation Disease and discusses possible etiologies, diagnosis, treatment and prevention.