according to Bulgarian Embassy website under the heading Consular Information, it states no visa required, you could always try the Embassy by phone to double check. Tonyt

The Slovak Republic is in the EU, and as one might expect Slovakian passport holders do not require a visa. See HERE

Remember that foreign citizens entering Bulgarian territory have to present a passport valid for at least three months beyond the holder's period of stay in Bulgaria.

Peter

(I see Tonyt and I are working together as often happens!)