Emergency services staff carried a man to the Otago Regional Rescue Helicopter in Alexandra yesterday.
Senior Sergeant Ian Kerrisk, of Alexandra, said the Alexandra man was trimming a neighbour's tree with a chainsaw, when he suffered a gash to his arm after falling more than 5m about 4pm.
A St John spokesman said the man suffered critical injuries and was flown to Dunedin Hospital's emergency department.
Snr Sgt Kerrisk said WorkSafe New Zealand was not investigating the matter, as the agency was satisfied it was not a workplace accident.