The Chicago Maroon student newspaper reported the accusations included seeing Alpha Delta Phi fraternity pledges wearing "oversized sombreros" as they did yard work while Latin music played, and a Facebook notice that Delta Upsilon fraternity planned a "Conquistadors and Aztec Hoes" theme party.
A post on the university's Web site from the dean of students said the school's "core value of rigorous and open inquiry is threatened" by such incidents, the Chicago Sun-Times reported Saturday.
A Delta Upsilon official told the Sun-Times in an e-mail late Saturday the fraternity publicly apologized and "deeply regrets that our initial event title and description offended members of the university community, and is taking steps to mend our relationships with the individuals and organizations that we have harmed."
The fraternity official said the event was canceled.
Students at Alpha Delta Phi declined to comment, referring the matter to a fraternity official, who also was unavailable for comment Saturday, the Sun-Times said.
In the school's Web post, Dean of Students Kimberly Goff-Crews said, "I am troubled by the impact such incidents have on the wider student community, as they conflict with our values as an intellectual community and harm our ability to fulfill our educational mission."
Regarding the "Conquistadors and Aztec Hoes" post, one student said it was "upsetting that people think it's OK, and it's promoting rape culture, so a lot of the female student groups are upset."
Regarding the report of lawn-mowing pledges wearing sombreros, another student said he's seen "a lot" of of Hispanic workers on campus who "might have been offended."