A government study finds that of the Iraq and Afghanistan veterans showing signs of post-traumatic stress, about a fifth are referred for mental health treatment.
A report from the Government Accountability Office says about five percent of interviewed veterans appear at risk.
Of those, about 22 percent are referred for more health care.
The GAO says the Defense Department can't guarantee that those who need referrals get them.
And investigators say the different military services don't seem to be consistent in deciding who needs help.
The assistant secretary of defense for health affairs offers another perspective on the findings.
In a response included with the GAO report, the Pentagon says a medical referral or treatment sometimes prolongs symptoms.
The department says rest and return to normal life can relieve combat stress.
The report found the Army and Air Force referred the highest percentage of veterans.
Then came the Navy.
The Marines were last with 15 percent.