Mycobacteriosis was diagnosed in five psittacine birds: a blue-headed pionus parrot (Pionus menstruus), three grey-cheeked parakeets (Brotogeris pyrrhopterus), and a red-crowned Amazon parrot (Amazona dufresniana rhodocorytha). Signs were marked muscular wasting, anemia, recurrent diarrhea, and dulling or loss of feathers. Lesions were commonly present in the intestines, livers, and spleens, suggesting an oral route of infection. Other tissues in which granulomas were found were the oropharynx, pancreas, and kidneys. The pionus parrot had pulmonary tuberculosis involving both lungs and air sacs. One grey-cheeked parakeet exhibited no gross tubercular lesions. Microscopic lesions varied from noncaseous histiocytic foci to granulomatous "tubercles" with caseous necrosis.