A 30-year old motorcyclist from Gosport who was travelling towards Whitchurch, died at the scene after a collision with a car travelling in the opposite direction.
The driver of the car, a 19-year old man from Basingstoke, was taken by Air Ambulance to Southampton General Hospital.
It is reported that the motorcyclist was riding a Triumph Dayton and the car was a Daihatsu Fourtrak.
The B3400 was closed from just after 6.00pm for several hours between Hurstbourne Priors and Andover with diversions in place.
Police are appealing for witnesses.
If you witnessed the collision, saw the vehicles prior to the incident, or have any other information that you feel might help, please call Whitchurch Roads Policing Unit on 101.