The pieces of bark were found at an excavation site near the Novgorod Kremlin's fortress wall on Wednesday and Thursday.
Experts said they dated back to the first part of the 12th century, based on the occupation layer and other signs.
Archaeologists did not disclose the texts. They only said one of the findings was a note written by a woman to her acquaintance in which she reprimanded the latter for not paying her debt. The other piece is said to be part of a larger document not found so far.
A total of 956 pieces of birch bark have been found near Veliky Novgorod in the past 54 years.
Scientists found three ancient documents during this excavation season.
The first bark document did not contain profanities, but was rather unusual. It said a Velikiy Novgorod resident, known as Shilnik, had stolen pigs and horses.
The Novgorod State Museum said the first ancient document containing indecent words had been found in the town of Staraya Russa, near Novgorod.
In it, a man was advising his brother on how to trade, recommending he remain silent and do as instructed.
Historians said half-jokingly if the author had known his letter would be found nearly a thousand years later, he would have signed it and thereby gone down in Russian history as the first foul mouth.
Add to blog
You may place this material on your blog by copying the link.
Image Galleries: Yury Gagarin: A down-to-earth person
Infographics: The Linguistic Diversity of the Planet
Ukraine has not preserved its 1991 borders. The signing of the Geneva memorandum on April 17 reaffirmed the willingness of Russia, the United States and EU countries to reach a compromise. While the sides continue to trade tough talk and symbolic sanctions, the Kremlin and the White House are also holding a parallel dialogue on the coordinated geopolitical revision of Eastern Europe.