A nine-year-old boy has died on a dairy farm in Kihikihi in the Waikato after his quad bike rolled.

The accident occurred on the farm on Arapuni Road just after 8.30pm on Wednesday. He had gone to round up the cows for milking but failed to return.

It appeared the bike rolled but police say the cause of the accident has yet to be determined.

An ambulance and two fire crews were called to the scene.