Visa is required for citizens of Bulgaria to visit Vietnam. Bulgarian nationals may have 2 options: Visit Vietnam embassy in Bulgaria (Sofia) or apply for a visa on arrival to Vietnam from Bulgaria online. Bulgarian citizens may apply for both tourist and business visa to Vietnam for the stay of 1 to 6 months from Bulgaria. Please check this link for visa fee for Bulgarian citizens.

All the information for getting a visa from Vietnam embassy in Bulgaria can be found here: http://www.vietnamembassy-bulgaria.org