You May Not Need a Visa
Holding another country's visa can be enough.
Since a 2014 government decision, holders of a valid Schengen, UK, EU member state or United States visa — and holders of a residence permit in the Schengen area, the EU or the US — may enter, transit and stay in Serbia for up to 90 days in a six-month period without applying for a visa first.
That covers a very large share of the people who would otherwise be reading a Serbian visa photo page. It is worth checking before you spend anything.
Serbia also accepts the two-passport case: an expired national passport carrying the valid visa or residence permit, presented alongside a valid national passport. Holders of a residence permit issued as a separate card, rather than a sticker in the passport, must present their valid passport at the border.
