A Territorial Army soldier from Hawick who died while serving in southern Iraq suffered a heart attack brought on by heat stroke, an inquest has heard.
Pte Jason Smith, 32, died while he was serving with the 52nd Lowland Regiment on 13 August 2003.
Home Office pathologist Nicholas Hunt said the damage caused by the heat stroke to Pte Smith's liver, brain and heart could not have been survived.
The inquest, in Oxford, is expected to last for three days.
Mr Hunt said Pte Smith's body temperature - which normally should have been about 37C - rose to 41.4C causing him to suffer a seizure.
He said the soldier, who was 6ft tall and weighed 105 kg (16st 7lbs), did not appear to have any of the features associated with heat stroke, including high blood pressure or infections.
An army doctor also told the inquest that all soldiers undergo a full medical assessment before their deployment.
Although she added there were sometimes problems getting access to soldiers' medical records from civilian GPs.
Lt Col Nicola Cordell said that a range of checks should highlight any medical condition which might affect a soldier.