[How to make differential diagnosis among hundreds of infectious diseases ?] Threre are hundreds of reportable, emerging and related infectious diseases worldwide. Many of them have many similar symtoms, and on the other hand a diasease may have different clinical symptoms and the severity of the same symptoms may be different in degree. It usually makes a physician difficult to make differential diagnosis among these diseases at the spot. Nevrtheless, the diagnosis can sometimes be easily made because of its very typical and unique symptoms like in the case of tetanus and rabies. Although, for the convenience of diferential diagnosis we may sort the main symptoms of infectious diseases into eight categories. It helps physicians make differential diagnosis easily. The classification of the symptoms and related diseasess with their reference websites is presented in the followings: (1) fever with conspicuous skin lesions, (2) fever without conspicuous skin lesions, (3) diarrhea, (4) upper respiratory symptoms, (5) neurological symptoms, (6) jaundice (icterus), (7) STD (sexually transmitted diseases), and (8) others. It will be updated at all times.