The letter of Neacșu of Câmpulung (Romanian: Scrisoarea lui Neacșu de la Câmpulung), (Old Romanian: Скрісѻрѣ льи дє ла Кымпȣлȣнг) written in 1521, is one of the oldest surviving documents available in Romanian that can be reliably dated. Written using Cyrillic, it was sent by Neacșu Lupu, a boyar from Câmpulung, Wallachia (now Argeș County, Romania) to Johannes Benkner, the mayor of Brassó, Kingdom of Hungary (now Brașov, Romania), warning him about the imminent attack of the Ottoman Empire on Transylvania.
Neacșu Lupu was a 16th-century Wallachian boyar from Câmpulung, the son of Neacșu Mircea, mentioned for the first time during Vlad cel Tânăr's reign (1510–1512), in documents related to a trial regarding debts between himself and merchants of Brașov. It is possible that he was himself a merchant involved in the trade of Turkish goods that he was buying south of the Danube and selling in Transylvania, which may explain his relationship with the mayor of Brașov.
The Letter of Neacșu of Câmpulung to Johannes (Hans) Benkner of Brașov was most probably written on the June 29 or 30, 1521, in the city of Dlăgopole (Old Bulgarian rendition/translation of Câmpulung, lit. "the long field"). The date is not mentioned within the letter itself, it being inferred from the historic events described and the people mentioned.
The letter was discovered in 1894 by Wilhelm Stenner, the archivar of Brașov.
The text of the letter was written in the Cyrillic script, and is composed of three parts. The introduction in Slavonic, translated: "To the most wise and noble and venerable and by God endowed master Hanas Begner of Braşov, all the best, from Neacșu of Câmpulung".