It has been estimated that one in every 20 children in England and Wales suffer from the medically-recognized condition that causes one to feel physically ill with the thought of school.
It can bring on physical symptoms such as vomiting, headaches, fatigue, and panic attacks.
Experts blame the trend towards bigger schools in the UK, as well as anxieties about childhood obesity and bullying, for this problem.
"The saddest thing about children going undiagnosed is that the phobia can lead to lifelong problems," the Telegraph quoted Dr. Nigel Blagg, a psychologist and author of School Phobia and its Treatment, as saying.
"All the evidence shows that the best way to deal with this is to get the child back to school and routine as quickly as is possible," he added.
Children are most likely to suffer from the illness between the ages of 11 and 12, when most pupils move from smaller primary schools to larger secondary schools.
The university experts fear that the anxiety phobias are likely to track into adulthood.