Two cases where multiple juvenile cockatiels exhibited inappetance, depression, upper respiratory signs, and "lockjaw" are described. Symptoms progressed over several weeks until all birds died, in spite of antibacterial therapy. Seven affected birds from each case were submitted for diagnostic evaluation. Microscopically, all birds had necrotizing rhinitis and sinusitis, as well as myositis, perineuritis and osteomyelitis affecting the jaw muscles and cranial bones. Multiple bacterial agents were isolated from the lungs and sinuses in both cases. Juvenile cockatiels appear to be particularly susceptible to temporomandibulitis, temporomandibular joint rigidity, or "lockjaw". Once chronic inflammation and fibrosis develop, it appears unlikely that jaw mobility can be restored.