During the tradition, known as San Lucas, older students submit their new young classmates to a massive food fight.
Photo: Jorge Guerrero/AFP
Important food fight provisions included flour and eggs.
To the chants of "uno, dos, tres, cuatro queremos sangre de novato" ("one, two, three, four, we want the blood of the newbies") new students were pelted with ketchup, mayonnaise and beans, among other messy foods.
Photo: Jorge Guerrero
Some students dressed up as their favourite film characters, here is Woody from Toy Story about to catch Buzz Lightyear.
The ritual is banned from inside university buildings so students take the fight to the streets.
The fight started in the Plaza de San Lázaro then made its way up the Avenida de la Constitución towards University Square.
After the fight, students were set to embark on a huge botellón or outdoor drinking session.