Napster has four days to block the free exchange of 135,000 copyright songs.
The recording industry has sent the list of songs to the music swapping service.
Napster has until Wednesday to block their free exchange on its online service.
"The Recording Industry Association of America planned to send the list to Napster electronically on Friday night", its spokeswoman Amy Weiss said.
Napster then would have three business days to block the songs, according to an injunction published by US District Judge Marilyn Hall Patel.
The injunction was issued based on a suit by record companies, which want to shut Napster down for facilitating copyright infringement.
The list, compiled from music owned by the big five record labels, arranges the songs by artist name, song title and album name. Also included are names under which the songs are stored.
Napster's website said it had received some notices and expected the record companies to send more.
"You will still be able to share music that we haven't been asked to block. The Napster file-sharing service is and will continue to be up and running."
Napster did not specify how many files were blocked, but a wide range of files remained available yesterday. A search of Metallica revealed more than 100 files on one server. A search of the band's name and the song The Unforgiven returned no results. Yet a search on The Un4given was successful.
PA