The Book of Boril or Boril Synodic (Bulgarian: Борилов синодик) is a medieval Bulgarian book from the beginning of the 13th century. It is an important source for the history of the Bulgarian Empire.

The book was written in conjunction with the Synod of Tarnovo (1211) convoked by tsar Boril against the Bogomils in 1211. Later additions and editions were made, dated at the end of XIV c.^[1]