The male was taken by air ambulance to Southampton General Hospital after his motorcycle came into collision with another car and a flat bed lorry on the A32 at Lower Farringdon.
Police are appealing for witnesses following the crash, which took place around 3.40pm near the Woodside Lane junction.
The A32 was closed for much of Friday evening while investigations took place.
Witnesses or anyone with information should call Hampshire Police on 101 quoting Operation Helix.