Rider Jason Dupasquier, 19, died after a crash at a Moto3 qualifying of the Italian Grand Prix on Sunday.
The Swiss was involved in a crash with Ayumu Sasaki and Jeremy Alcoba in Saturday's race. Dupasquier fell and was hit by Sasaki's motorbike and his bike.
"Despite the best efforts of circuit medical staff and all those subsequently attending to the Swiss rider, the hospital has announced that Dupasquier has sadly succumbed to his injuries," MotoGP announced in a statement.
He was helicoptered to a hospital in Florence after an immediate treatment besides the track and was announced dead on Sunday.
He raced his second season in Moto3 and was in the top 10 in the overall standings.
His team, Prustel GP pulled out of Sunday's race, when the MotoGP had a one-minute silence ahead of the 23-lap race.