The 125cc and 250cc race winner, who raced in the top 500cc class from 1996-98, was taking part in the 'Sic Supermoto Day' in memory of the late Marco Simoncelli at the Latina circuit in Italy.
Romboni was struck by another rider after crashing during one of the practice sessions for the event on Saturday.
The 44-year-old was taken to the Santa Maria Goretti hospital in the Latina area, but he succumbed to his injuries from the incident.
Romboni managed to finish fourth in the 125cc and 250cc world championships during his career, taking wins at both levels before graduating to the 500cc class with Aprilia for 1996.
However, his time at the top level was not as successful as the Italian manufacturer struggled, and he took a best finish of third in the 1997 Dutch TT at Assen.
- Sports & Recreation
- Marco Simoncelli