An Auckland harness-racing driver is in a serious condition in hospital after being knocked unconscious during a race at Alexandra Park as family members watched on.

Frank Cooney, who is in his 60s and has over 40 years industry experience, was thrown from the sulky pulled behind the horse during the first race of the night about 6.30pm on Friday.

"I think Frank's horse has basically hit a cart in front of the horse and the horse has fallen onto the track and Frank's been catapulted from the sulky, hit by another horse, then hit the track," park racing manager Kevin Smith told NZ Newswire.

"This kind of thing is very infrequent but I guess when you're racing a horse this kind of thing can happen."

Mr Cooney's sister-in-law and other family members were watching the race and witnessed the accident.

His wife was at his bedside on Friday night, Mr Smith said.

Mr Cooney is being treated at Auckland City Hospital and is in a serious but stable condition, a hospital spokesman told NZ Newswire on Saturday morning.

He was put into an induced coma on Friday night but a CT or head scan showed his condition was "looking pretty positive", Mr Smith said.