A man is being questioned by police after his ute struck and killed a cyclist in northern New South Wales.

Police say a 66-year-old was riding on Ewingsdale Road in Byron Bay when he was hit by the ute about 8.15pm (AEDT).

A police spokeswoman, Joanne Elliot, says the bicycle and ute were both travelling west when they collided.

"The man was thrown onto the bonnet," she said.

"He suffered severe head injuries and, whilst several people stopped to help and police arrived on the scene and commenced CPR, unfortunately he died at the scene.

"The 43-year-old man who was driving the ute had also stopped and is obviously assisting police."

Police say the cyclist was wearing a helmet.

The ute driver returned a negative result to a roadside breath test and has also undergone mandatory blood and urine tests.

Police believe both men are from the Byron Bay area.