The collision took place at 2.15am and the car failed to stop at the scene.
The man from West Lulworth was admitted to hospital with serious injuries and he needed what police are are calling a surgical procedure.
Anyone with information about the identity of the driver at the time of the incident should contact the Weymouth Traffic Department on 101,quoting incident number 321 of the 3rd August.
More top news
Essex Police say pictures of boys undressing have been discovered in the home of a teacher who's been found dead.
Organisations are calling for the release of Chinese sky lanterns to be banned due to the risk they pose to wildlife and habitats.
Two kittens are looking for a new home after being dumped in a Hampshire car park.