TWO more Tasmanian devils, vaccinated with a trial vaccine potentially capable of saving the species, were killed on Saturday.
The deaths came just days after two other devils died on the roads.
The devils were part of a trial group of 20 that were released into the national park on September 25.
The healthy devils, 19 of them vaccinated, were released into the wild after previous trials of the vaccine at the University of Tasmania's Menzies Institute for Medical Research found that it was possible to activate an immune response against cancer cells.
The two devils were found on the Frankford Highway near the turn-off to Narawntapu National Park on Saturday morning.
Save the Tasmanian Devil Program team leader Samantha Fox said that aside from the Devil Facial Tumour Disease, road-kill was the greatest threat to devils.
"Both animals will undergo a post-mortem examination on Monday to confirm the cause of death but it appears their injuries are consistent with trauma from being struck by a motor vehicle," Dr Fox said.
"We urge all motorists to consider this when driving at night.
"Driving slowly is not only good road safety sense but is also good for Tasmania's wildlife."
Staff from the program will return to the park at intervals over two, four, eight and 12 weeks to monitor the devil population.