"My father is losing weight. He suffers from pains in the heart and has blood pressure problems. He has had two strokes already," said Zainab Aziz after visiting him on Friday.
Aziz, 70, once the public face of Saddam Hussein's government abroad, was jailed after the US-led invasion of Iraq in 2003.
No formal charges have been brought against him and he remains in US custody.
A US official on Thursday denied there had been any significant deterioration in Aziz's health and said he was
receiving professional care from medical staff at his prison.
Weeks from death
Badie Arif Ezzat, Aziz's lawyer, said on Thursday that Aziz's health had sharply deteriorated in recent weeks and that he may be only weeks away from death.
Zainab Aziz, who spent 30 minutes with her father on Friday,
said he looked better.
"But that doesn't mean he is okay. He looked very tired.
Lawyer Badie Arif Ezzat (L), said
Aziz was weeks from death
"We demand that he be released, not only because he is very sick but also because he is 70 years old and he has been detained until now without any charge.
"His health is very bad, and anyone in his case may collapse fast, especially when they have so many illnesses."
She said she and her father discussed only family matters during the visit.