Greer, speaking about her contentious new history book 'Shakespeare's Wife', suggest that Shakespeare contracted the disease when he was a young man, and that this was the cause of his death.
"The likely cause of Shakespeare's death was syphilis, contracted when he was a young man," The Independent quoted her, as saying at the Edinburgh International Book Festival.
However, she also admits that his bones, which could show the signs of the disease, will never be found.
Greer criticised generations of "demeaning and mean-spirited" male academics for perpetuating the belief that Shakespeare was forced to marry Anne Hathaway, a "complete slag... the town bike" when she became pregnant.
Instead, she claims that the marriage took place not out of a sense of duty, but love.
Greer is also of the opinion that Hathaway was Shakespeare's 'business angel', and that she was the one who paid for his collection of plays to be published and preserved.
"I argue that the only way the folio was ever published is that somebody paid for it. There was an angel, somebody who was determined that the work that cost so much for her would not disappear into the morgue of time. I think she gave the money," she said.
"It is liberating to consider the possibility that a wife made a material contribution to the greatness of her husband. Why has it never been countenanced? All the literary wives you have heard of were considered to be frail, faulty and not worthy. I say the wives of great authors are essential to their success, whether the academic establishment has realised it or not, and we might as well begin at the top, with the wife of the man of the millennium," she added.
'Shakespeare's Wife' is due to be published at the beginning of September this year.