The rapper had been battling cancer and sources close to him say he was admitted to the hospital in February after suffering cardiac arrest. He had been in a coma since then and died Monday night.
Guru, born Keith Elam in Boston, is best known as co-founder of the rap duo Gang Starr.
Guru apparently had written a note saying goodbye to his family and friends. In the letter, he wrote that he had suffered from cancer for a year and had exhausted all of his medical options.
He also stated that he did not want his ex Gang Starr partner, DJ Premier to use the duo's name for the purpose of any tributes or business deals. He said they had not had a relationship in recent years.
Formed in 1985, Gang Starr released six albums.