FUO workup has changed. True, it’s still 3 major categories, infection, malignancy and inflammation, but travel associated workup needs to investigate special pathologies (Table 10.2), I found Haider class based on Haider classification (Table 10.1) as the most comprehensive classification as of today. Other than infection, drug-related fever should be considered and onset from the exposure gives us important clue (Table 10.3). And also be aware who needs blood cultures and needs follow up Bcx (Table 10.4).