The sexual revolution of the 2Ist century, by changing drastically sexual culture and practices, has made absolutely necessary special programs of sexual education for children and youth. Scientific knowledge about human sexuality is a precondition of sexual and reproductive health Access to sexual information is one of the basic human rights. Liberalization of sexual morality without appropriate information about the involved sexual risks inevitably produces an increase of unwanted pregnancies, abortions, STDs and HIV. WHO, UNAIDS and other international organizations unanimously consider sexual education as a global issue of the 21st century. However, the introduction of such programs is related with serious social and educational difficulties. That is why it has strong ideological opposition. The author compares two main rival world strategies - US strategy of complete sexual abstinence until marriage and European models of comprehensive sexual education - and comes to the conclusion that, according to reliable social and medical statistics, alternative European strategies are much more effective and realistic. The necessity of close cooperation between medical sexuologists, social scientists and educators is emphasized.