Twelve primary tumors occurred in birds, and of these five were found among parrakeets, they being curiously enough all of the same type. These cases were all discovered in the undulated grass variety (_Melopsittacus undulatus_ ♂ ♂ ♂ ♂ ♂ ) and, because of this fact and their histological similarity, have excited interest. Grossly they are irregularly nodular or lobulated tumors usually springing distinctly from one lobe, but sometimes destroying the whole organ; they are soft, resilient and hold their place well during manipulation. Sometimes one may detect the topography of the renal lobes on cross section while at other times the mass is homogeneous. Microscopically one finds the structure of papillary adenoma with cystic formations or the production of atypical solid nests of epithelia which would have to be called cancerous, for they certainly make no attempts to retain acinus or duct groupings. Carcinomatous areas have been discovered in two of these cases, not in the other three, which have been called papillary adenoma. One of the tumors was subjected to many sectionings and different stainings techniques to discover, if possible, animal and vegetable parasites; this search failed. One of these tumors produced hemorrhage by rupture of a pyramid but extension to adjacent tissue and metastases have not been seen. Pathologically these must be classified with the tumors but because of the number of closely similar growths in the same avian species housed in the same enclosure, the possibility of a parasitic cause will not be forgotten. The remaining seven renal neoplasms are made up of two adenomata in a Jungle Babbler, (_Crateropus canorus_) and a red headed duck (_Fulligula ferina americana_), two adenocarcinomata in a saffron finch ♀ (_Sycalis flaveola_), and a chestnut-eared finch, ♂ (_Amadina castanotis_), two hypernephromata in an American robin, ♀ (_Planesticus migratorius_) and a European blackbird, ♀ (_Merula merula_), and a spindle celled sarcoma on a scaly ground dove ♀ (_Scardapella squamosa_). One adenocarcinoma sent out metastases to the lung, one hypernephroma had secondary growths in the lungs, the other in the liver. The sarcoma case presented a metastasis in the tibia.