Four of six cockatiels died within a week after being purchased from a commercial breeder. A fifth bird was euthanatized and necropsied during this time, and tissues were collected for microscopic examination. The small intestine had moderate numbers of Cryptosporidium sp. parasites present. A few large, basophilic intranuclear inclusions were present in renal ductular epithelium. Cryptosporidium sp. oocysts were found in the feces of the surviving bird. Thirty oocysts were 7.2 by 5.5 microns. The shape index was 1.31. Morphological examinations of the fecal oocysts indicated that the Cryptosporidium species infecting the cockatiels was similar to C. baileyi, a parasite that is not usually associated with small-intestinal infections.