AP
Republican presidential candidate Donald Trump speaks at a rally organized by Tea Party Patriots in on Capitol Hill in Washington, Wednesday, Sept. 9, 2015, to oppose the Iran nuclear agreement.
In the interview with Rolling Stone, Trump took a tone of "disgust" describing Fiorina's appearance during a television interview.
"Look at that face," he said, according to Rolling Stone. "Would anyone vote for that?"
"Can you imagine that, the face of our next president?" he added.
It's far from the first time Trump has made questionable remarks during his three-month-long presidential campaign - especially regarding women. After the first Republican debate last month, he launched an off-and-on, weeks-long attack on Fox News host Megyn Kelly, who he accused of asking him unfair questions as a debate moderator.
The resulting feud between Trump and Kelly included episodes during which the real-estate magnate retweeted supporters who had called Kelly a "bimbo."
He also said during one interview that she had "blood coming out of her eyes, blood coming out of her - wherever" during the debate, a comment many interpreted as a lewd remark that referred to menstruation. (Trump later insisted he meant "nose" or "ears." "Only a deviant would think anything else," he added.)
Fiorina, who appeared on Kelly's Fox News show Wednesday night, said Trump's comments "speak for themselves."
"Maybe I'm getting under his skin a little bit," she said.
Fiorina, the former CEO of Hewlett Packard, has surged in polls following a strong performance in the first lower-tier GOP debate. Last week, CNN changed its rules for next week's upcoming debate, meaning she will almost certainly be on the main stage.
The multiple controversies of the first three months of Trump's presidential campaign have done little derail the candidate's momentum.
Despite sharp insults against war veteran and Arizona Sen. John McCain (R) and, more recently, a dust-up with respected Univision journalist, Jorge Ramos, Trump maintains a solid lead against his GOP competitors.