It affects those in the University Hall and Ilam Student Accommodation.
Executive director of people, culture and campus life Paul O'Flaherty said the university became aware overnight of the scale of the problem and was working with the National Public Health Service to investigate the cause of the illness.
He said while students appeared to be recovering well on Monday, they have been directed to the university's accommodation providers UniLodge if they needed free electrolyte mixes for dehydration, bottled water and packaged meals.
Students unable to sit exams can apply for special consideration and may be offered a resit of their exams in the next couple of weeks.
Dr Claire Salter, public health medical specialist for the National Public Health Service, said the service was aware of the outbreak.
"The National Public Health Service was notified of a potential gastroenteritis like illness outbreak at a university hall this morning," she said.
"We are working closely with the university to identify the cause of the illness and have arranged to collect samples for testing.
"Any students experiencing diarrhoea, please visit the Health New Zealand website for information about the treatment of diarrhoea. It's important to keep your fluids up and careful handwashing is the most important way to prevent the spread of diarrhoea.
"Most students will not need medical treatment, however, if you are unsure, you can contact your usual health care provider or ring Healthline for advice 0800 611 116."
