At the beginning of 21 century endemic areas of yellow fever are in tropical forests of Africa and South America, covering 43 countries of the around the world. In a period of 11 years 2005 citizens from 14 countries of Africa and 871 citizens from 8 countries of South America were taken ill with of a yellow fever. On the both continentals were observed distinct, limited (no more than 40 people) ictuses of urban of a yellow fever related to mosquito Aedes aegypti. Still, the total mortality is high--up to 35%. The systems of epidemiological surveillance and informational connection are created; the live vaccine in sufficient amount for general is delivered to the hot spots of disease. Civil wars and ethnic conflicts hinder the introduction of compulsory vaccination in national calendars of the inoculation of children in endemic countries. Because of it the vaccination is realized slowly: nowadays the vaccination is introduce in 19 among 25 countries of Africa with high risk of disease.