Understanding the normal anatomy of psittacine birds is basic to the diagnosis and treatment of disease in these species. As a first step toward a systematic investigation of the avian cardiovascular system, we conducted a 2-part study of healthy and diseased parrots. In the first part, the normal heart shape, size, and weight were studied in budgerigars (Melopsittacus undulatus) and Australian king parrots (Alisterus s scapularis) that were euthanatized because of genetic feather abnormalities. To compare results of birds of different sizes, measurements were evaluated in relation to the length of the sternum of the individual bird. Only minor differences were found between the 2 species studied. In the second part of the study, the spectrum and the frequency of pathologic changes of the heart and the major vessels were evaluated in 107 caged psittacine birds that were presented for routine necropsy. Of the birds examined, 36% had visible gross lesions of the heart, the major vessels, or both. On histologic examination, 99% exhibited at least low-grade pathologic changes of the heart or major vessels, which frequently were associated with noninfectious diseases. The results of this study emphasize the importance of cardiovascular disease in captive parrots.