Serbia Passport and Visas Information
Getting into Serbia does not constitute a problem for most European nationals. You don't need to obtain a visa for entering. Citizens of USA, Canada and Australia and the European Union do not need visas either. Citizens of Bosnia need only ID. Check with your nearest Serbian embassy for current and detailed information.
Serbia has announced that visitors with Kosovan visas or passport stamps will not be allowed into the country. In practice, officers seem content with simply crossing them out and replacing them with Serbian ones, but it would be foolhardy to rely on this. Likewise, leaving Serbia via Kosovo is not considered leaving the country, so you run the risk of being charged with overstaying if you ever return.Source: Wikitravel.org