Augusto Pierantoni (June 1840 in Chieti; March 12, 1911 in Rome) was an Italian jurist, professor, and politician in the Kingdom of Italy. He was also one of the founding members of the Institut de Droit International.
Pierantoni was Ministerial Secretary in Turin, and later a professor of constitutional law and international law at the Universities of Modena (1865), Naples (1871) and Rome (1876). He also was a member of the Italian Senate in 1883. In 1885 he represented his country at the Paris Conference on shipping in the Suez Canal.
In September, 1873, together with ten other lawyers from various countries he founded the Institut de Droit International in the Belgian city of Ghent. This was a private organization concerned with the development of international law. For his work in international law, he was nominated for the Nobel Peace Prize in 1904, but the Institut as a whole received the award for that year.
He was married in 1868 to the poet Grazia Mancini, a daughter of the lawyer Pasquale Stanislao Mancini who was also a founder of the Institut de Droit International and its first president.
