In 1765, he took part in burning of books "harmful to the society" at the order of Catherine the Great. During the plague outbreak in 1771, which caused mass departure of landowners, city officials, and rich merchants from Moscow, Pyotr Saltykov asked Catherine the Great for permission to leave the city. Without waiting for her reply, he left for his Marfino estate on the outskirts of Moscow. After a plague riot had broken out in Moscow on 16 September, Saltykov returned to the city. However, Catherine the Great relieved him of his post on 13 November 1771. A year later, he died on his estate at Marfino.