Four in ten teachers say they're seeing children arriving at school hungry every day.
A survey by Kellogg Ireland, of 211 teachers at primary and secondary level, found 78% say children are hungry in their classroom at least once a week.
The research shows more than half of teachers say the number of hungry children in their class has increased over the past year.
Nearly two-thirds of teachers say a lack of food is having a significant impact on the educational progression of children affected.
71% of teachers surveyed report children being tired, while 67% say hungry children find it much harder to concentrate in class.
Shane Loftus, Principal of Our Lady Immaculate School in Darndale in Dublin, says it's becoming a massive worry for principals.
"We would've seen this for a long time, but now talking to colleagues who are working in what you could refer to as more affluent areas they're now seeing it.
"So people are often calling me asking what do you do in your school, and looking for advice maybe on how to alleviate the problem in their schools now as well".
