The Ministry of Defence is insufficiently prepared for a significant increase in military casualties, according to a cross-party committee of MPs.
The Public Accounts Committee (PAC) called for better contingency planning for the treatment of seriously injured soldiers should its facility at Selly Oak become full.
Most seriously injured troops are taken to Selly Oak Hospital in Birmingham after their return to the UK. They are then often moved to Headley Court in Surrey for rehabilitation.
The PAC praised the treatment provided in recent years, saying that soldiers are surviving now who would have died in previous wars.
Some 565 service personnel have been seriously injured in Afghanistan and Iraq since October 2001.
But the committee said it is concerned that there is only a voluntary agreement with the NHS that soldiers would be taken to other West Midlands hospitals if Selly Oak is full.
It also urged that the "military culture" at Selly Oak would need to be transferred to any new sites for soldiers.
"The department does not have sufficiently detailed and robust contingency plans should Selly Oak become full," the PAC said in a report.
"Injured military personnel should be treated in a military environment which is suitable for their needs.
"If Selly Oak remains under pressure for more than five days there are arrangements for military patients to be treated in other hospitals across the UK, but these arrangements need strengthening."
It added that the Ministry of Defence needs a "more robust" plan detailing which NHS hospitals military patients would go to, and how it would replicate elsewhere Selly Oak's expertise and experience with serious battlefield injuries.
The PAC said that a further "long-term challenge" for the Ministry of Defence, the NHS and other Government departments is the lifelong care a growing number of soldiers need.
The arrangements for their support after leaving the armed forces is still widely untested as few have been discharged.
"The department now needs to work with wider government to put in place an overarching system to ensure that soldiers' clinical care and support for their families is maintained in the longer term," the committee said.
"This system should include a clear, costed plan to provide this care and support, and arrangements for monitoring the accessibility and standard of care for veterans."
Tory MP Edward Leigh, chairman of the PAC, said the Ministry of Defence and its medical staff are providing care that compares "favourably" with the best NHS hospitals.
"What concerns us is the extent to which the MoD would continue to be able to provide that high standard of care if the casualty rate were to increase significantly," he said.
"Selly Oak Hospital, where returning casualties are first treated, offers injured troops a military culture and environment, expertise in dealing with serious battlefield injuries and wider support for families."