In 1981 he quit his first single Oceania which is presented in a singing competition to discover new talent within the program on Sunday that presented by Pippo Baudo, the song on the back, fragile blood, sees Minghi as co-author of the music. \r The year after Castelnuovo participate in the Festival of Sanremo 1982 with Seven-wire hemp, a piece that gives the title to his first album, produced by Minghi yet, and collecting some success. \r In 1982 Castelnuovo makes his first tour, along with two other artists to labels distributed dall'RCA Italian, Marco Ferradini and Goran Kuzminac: to launch the tour is running a Q Disc of the three artists, with a song, well the garden, sang along and three individually sung, the song is Castelnuovo Why not smile?. \r Back in San Remo in 1984 with what is certainly his most successful song, Nina, contained in album of the same year entitled Mario Castelnuovo, whose text is inspired by real events of the parents of Mario, conosciutisi during the Second World War . \r In 1985, the album is public piazza del Campo, which differs from the sounds of the disks before and that pursues a more sound research, which follows, in 1987, Venus, which contains the song Madonna di Venere presented in San Remo the same year ; The previous year instead participated as author of the song Man yesterday, played by Paola Turci, who Castelnuovo (which the disc of the singer performs songs in the final) will run only live without influence. \r 1988 sees the publication of the disc Over the Cuckoo's Nest: in songs you can listen Mariella Nava, at the beginning, who also plays the piano and Castelnuovo which makes the tour of that year.