Four cases of septic subdeltoid bursitis are described. Clinical presentations, microbiology, and therapies are reviewed for these cases as well as for the six previously reported cases in the literature. The etiology of septic subdeltoid bursitis was related to bacteremia, trauma, or immune incompetence. Compared with septic oelcranon and prepatellar bursitis, septic subdeltoid bursitis was associated with a more profound inflammatory reaction in the bursa, required more sophisticated diagnostic imaging, and necessitated more aggressive therapy. Appropriate therapy generally resulted in favorable outcomes.