Like the other Apostles, the holy Nathanael or Bartholomew, a true Israelite, sincere and without guile, as Our Savior Himself testified, was honored with a vigil which was already noted in the Martyrology of St. Jerome.

The Mass is that of December 20, but at Rome the Office of today was not introduced until much later.

(Source: The New Roman Missal, Rev. F. X. Lasance)