Palo was suspended Sept. 7 after being charged with sexually abusing a woman he was driving home earlier this year. Online court records say Palo's attorney, Matthew Boles, filed a written plea of not guilty on Tuesday.
Palo and another man, 21-year-old Spencer Cruise, of Ames, were charged with second-degree sexual abuse. The criminal complaint says the men offered to give a woman a ride home on May 18, but instead drove her to a home owned by Cruise's family and "committed a sex act by force against the victim's will."
Online records show that Cruise hasn't entered a plea.
Iowa State coach Fred Hoiberg has suspended Palo, a reserve guard.