President Bush has intervened in a scandal over the way wounded American soldiers were treated after they returned home from Iraq or Afghanistan.
Mr Bush said the soldiers deserved the best care America could provide
In his weekly radio address, Mr Bush said he was "deeply troubled" by the treatment of some military veterans in a Washington medical centre.
The Washington Post said last week that some of the soldiers lived in buildings infested with rodents and cockroaches.
The army secretary and the medical centre's head quit over the reports.
'Deserve the best care'
In his address, Mr Bush said the treatment of some wounded veterans at Washington's Walter Reed hospital was "unacceptable".
"These servicemen and women deserve the thanks of our country, and they deserve the best care our nation can provide," he will say, according to the text.
"That is why I was deeply troubled by recent reports of substandard conditions at Walter Reed Army Medical Center."
He said most staff at the centre care deeply about the troops and work day and night to help them, but some veterans have experienced problems with bureaucracy and living conditions.
"This is unacceptable to me, it is unacceptable to our country, and it's not going to continue," he said.
Mr Bush added that he was creating a bipartisan commission to review the medical care provided to wounded troops.
The Washington Post newspaper claimed in a series of articles that conditions at Walter Reed, the most famous veterans' hospital in the US, were poor.
Outpatients lived in rat-infested rooms and bureaucracy got in the way of those trying to provide help to often badly injured soldiers, the articles reported.
The scandal over conditions at the hospital erupted last week
The BBC's Justin Webb in Washington says that America's wounded veterans are regarded by most people in the country as truly heroic, so the fall-out has been considerable.
Defence Secretary Robert Gates said he was "concerned that some do not properly understand the need to communicate to the wounded and their families that we have no higher priority than their care".
"Our wounded soldiers and their families have sacrificed much and they deserve the best we can offer," he added.
For many Americans it is a shock to discover that the men and women they care so deeply about have been so badly let down, our correspondent says.
The resignation of Army Secretary Francis Harvey came a day after the head of Walter Reed Army Medical Center, Maj Gen George Weightman, was sacked.
Mr Gates was said to be angry at the way the army had handled the original allegations.
Have you been treated at the Walter Reed hospital? Send us your experiences using the form below.
The BBC may edit your comments and cannot guarantee that all emails will be published.