The victim, who was in his 20s, died following a two vehicle road traffic collision at Crossgar Road in Saintfield yesterday evening, Saturday, November 26.
The man died in hospital from his injuries following the collision between his motorcycle and a car at around 5.40 pm.
The Crossgar Road was closed for a number of hours and re-opened at around 1.45 am this morning.
Inspector Lynsey Barr has appealed for anyone who witnessed the collision to contact police in Downpatrick or officers at the Collision Investigation Unit on 101.
Last night, a teenage boy died in hospital after a hit and run collision in Coleraine.
The driver of the white car was later arrested in the Magherafelt area.
He is currently being questioned about causing death by dangerous driving, failing to stop and failing to remain at the scene of an accident and failing to report the accident.
The two deaths bring to 63 the number of people killed on Northern Ireland’s road so far this year.