Boris Godunov is a tragic opera in a prologue and four acts by the Russian composer Modest Petrovich Mussorgsky (see Mussorgsky, Modest). The opera's libretto (text), written in Russian by the composer, is based mainly on a Russian play written in 1825 by the Russian author Alexander Pushkin (see Pushkin, Alexander). Mussorgsky made two versions of Boris Godunov, adding some scenes and dropping others for the second version. The opera received its first complete performance, after many extensive revisions, in St. Petersburg, Russia, on Feb. 8, 1874.