The first horses have left the gate at the Herald's Boxing Day Races at Ellerslie.

The sun's beating down on the near 20,000 who've turned out for food, drinks, horse-racing and fashion.

Racing Club chief Cameron George said they've sold thousands of tickets, but there is still space on the infield.

"There's plenty of time, the last race is at 6.10 tonight, and all of our hospitality areas shut at 8."

He said it would be an exciting day, and encouraged people to get along to it.