A Perth woman has admitted duping two men out of thousands of dollars each, convincing both she had cancer in an elaborate con.

Rebecca Gray pleaded guilty to three counts of fraud in court today after the duo realised they were being double-crossed.

It's alleged Gray was in a relationship with both men at the same time - neither of whom had any idea of the other.​

One of the men, Sean Fry, says he subsequently found out had lied to them both about her condition and medical needs - for more than a year.​

He said they both, unbeknownst to each other, helped support her and raise her toddler before they realised it was an elaborate ruse.

Speaking outside court today Mr Fry said he had no reason to suspect she would lie about her medical condition.

Camera Icon Sean Fry said he had no reason to suspect his then partner was lying about having cancer.

“Who would do that?” He told 7 News Perth.​

“You just don't think someone who tells you they've got cancer, doesn't have cancer.

“You just wouldn't think someone would do that.​

"She's basically taken advantage of us and we've looked after her and every time she's gone over to his place she was telling me she was having her liver drained or a blood transfusion or a spinal tap or really in-depth medical procedures that never happened.​”

Between them they lost $11,000, but Mr Fry added it was not the money that upset him the most.

“The last six months has been about getting back in touch with the kid that she wouldn't let us see."​

Gray is due to face court again in December, where she will be sentenced.