Senior Constable John Mawhinney, of Tapanui, said the truck was travelling on West Otago Rd when the driver lost control on a moderate right-hand bend shortly after 8am.
The truck and trailer unit rolled off the road about 5km from Waipahi, through a fence and into a paddock.
The driver suffered minor injuries.
No other vehicles were involved.
St John and volunteer firefighters from Tapanui and Pukerau attended, while forestry equipment was used to clear logs from the roadside and the paddock.
The road was reduced to one lane until 12.30pm, when emergency services left the scene.
Snr Const Mawhinney said it was very foggy at the time, but police were uncertain whether that was a contributing factor to the crash.
An investigation was under way.
