Police found the woman's body on a property along Glen Ayr Road, in Girvan, about 8.30pm on Monday.

It is believed she fell from the horse while riding at the property, owned by a friend, on Sunday.

The alarm was raised by colleagues on Monday after the woman did not attend work and could not be contacted.

Police said the owner of the Glen Ayr Road property went out to search for the woman, finding her car and the horse she had been riding, which was still saddled and grazing in a paddock.

A search of the 100-acre property was launched about 6pm on Monday, after she was officially reported missing.

Port Stephens police, the dog squad, police rescue and the Westpac Rescue Helicopter swept the area.

The woman's body was found in a grassed paddock 2½ hours later, near a rocky dirt track.

Police said initial investigations indicated the woman, who was found with no helmet, had likely been thrown or fallen from the horse.

A crime scene was established and forensic investigators attended.

A post-mortem examination was scheduled to be carried out on Tuesday and a report will be prepared for the coroner.