A 41-year-old active duty U
S. Air Force enlisted man with a 3-week history of fevers, arthralgias, and myalgias. A 41-year-old active duty male was transferred to Walter Reed Army Medical Center in Washington, DC, for further evaluation of fever, rash, myalgias, arthralgias, and respiratory failure. An extensive evaluation with input from numerous subspecialties of medicine was performed. The patient was eventually diagnosed with adult Still's disease, which is a diagnosis of exclusion. This case illustrates the importance of having a broad differential diagnosis when evaluating a patient with fever of unknown origin, with emphasis on the approach to young, active duty military personnel.