Born in Rome, Gregoretti entered RAI in 1953, working as a documentarist and a director.

[2] In 1960 he won the Premio Italia Award for tv documentary La Sicilia del Gattopardo.

[2] Since 1978 he started his activity on stage as director of prose and opera representations.

[2] His activity as director was mainly characterized by a sensitivity to the political and social issues combined to a peculiar use of irony and satire.

[2][3] He was president of Teatro Stabile di Torino, the Turin Permanent Theatre, 1980 thru 1989, and in 1995 he was appointed president of the Accademia Nazionale di Arte Drammatica Silvio D'Amico.