A stroke was the final blow that killed Arafat, but it is not clear what disease or illness lead to a deterioration in his health, The New York Times concluded in its report on Thursday.
The records show that Arafat's symptoms make it highly unlikely that he died of Aids or poisoning, the newspaper said.
But Palestinian doctors continue to insist that he was poisoned, The New York Times reported.
While the Israeli Haaretz daily cites experts as saying that Arafat died of Aids, poisoning or an illness, it points out that the medical report states that "a discussion among a large number of medical experts ... shows that it is impossible to pinpoint a cause that will explain the combination of symptoms that led to the death of the patient".
Arafat's personal doctor, Ashraf al-Kurdi, who did not treat Arafat in his final weeks, said that he knows French doctors found the Aids virus in Arafat's blood, Haaretz reported.
The virus given to Arafat by Israel was used to disguise poisoning, he said, according to the newspaper.
Arafat died in a Paris hospital 11 November at the age of 75.
He had fallen ill in mid-October and doctors originally said he had the flu. The Palestinian leader was flown to Paris at the end of October, where he was treated until he died.