The man was taken to the Kingwood Medical Center after he was reportedly "coming in and out of consciousness."
According to airport officials, he was found near a ramp at Terminal E.
Eyewitness News listened to emergency radio traffic as first responders tried to figure out what happened.
"Person has taken off all their clothes and passed out," the woman said on the radio traffic. "Terminal E, gate E7, on the ramp. Says the patient has no clothes and passed out. EMS is en route."
Those calls were recorded at about 9:15 p.m. on Saturday.
Although details are limited, airport officials told ABC13 that the man was not an employee but he was in a restricted area.
"An investigation is underway to establish the full circumstances of the incident," the Houston Airport System said.