Avian mycobacteriosis has been documented commonly in poultry, companion birds, and birds in zoological collections or wildlife parks. However, reports in free-ranging raptors are relatively rare. We describe 6 cases of mycobacteriosis in free-living raptors. Four red-tailed hawks (Buteo jamaicensis), 1 red-shouldered hawk (Buteo lineatus), and 1 great horned owl (Bubo virginianus) were presented for examination after being found on the ground unable to fly. Common clinical findings in these birds included coelomic distention or palpable coelomic mass, nonregenerative anemia, and leukocytosis characterized by heterophilia, monocytosis, and lymphopenia. Results of radiography, ultrasonography, coelomoscopy, and biopsy, in combination with acid-fast staining of specimens obtained by biopsy or fine-needle aspiration, provided evidence of a presumptive diagnosis of mycobacteriosis. All birds were euthanatized (n = 5) or died (n = 1). At necropsy, diffuse granulomas with intralesional acid-fast bacilli were present in all birds. Mycobacteriosis was confirmed by culture in 4 birds, and polymerase chain reaction testing confirmed Mycobacterium avium in 3 of these 4 birds. On the basis of clinical and postmortem findings, mycobacteriosis should be considered as a differential diagnosis in adult raptors that are found debilitated and in poor body condition. Detection of acid-fast bacilli in biopsy or necropsy specimens allows a presumptive diagnosis of mycobacteriosis; however, definitive diagnosis requires mycobacterial culture or polymerase chain reaction analysis.