March 27 marks the day of the Theodorov Icon of the Mother of God, which is venerated in the Russian Orthodox Church as miraculous. This icon of the Virgin Mary is kept in the Epiphany Cathedral of the Epiphany-Anastasiia Monastery in Kostroma.

For three centuries, the Theodorov Icon was the patroness of the Romanov House and the protector of the Russian state.

In 1613, the Zemsky Sobor elected Mikhail Romanov to the throne, which was confirmed by the Sobornaya Oath. After that, an embassy was sent from Moscow to the Kostroma Ipatiev Monastery, where Mikhail Fyodorovich lived with his mother, the nun Marfa. According to later traditions, the Theodorov Icon played a special role in this event.

Since the late 18th century, German princesses who married Russian grand dukes and converted to Orthodoxy received the patronymic Fyodorovna in honor of the Theodorov Icon. Among them were Maria Fyodorovna (wife of Paul I), Alexandra Fyodorovna (wife of Nicholas I), Maria Fyodorovna (wife of Alexander III), Alexandra Fyodorovna (wife of Nicholas II), and Elizabeth Fyodorovna.