A school sent home seven girls because it said their knee-length skirts would 'ride up' while they were walking, sitting or climbing stairs.
One girl said a staff member asked to check the waistband on her skirt to see if it was rolled up.
Two others went back to Waterhead Academy in Oldham, Greater Manchester, with what they believed was the correct length of skirt - but were sent home again because it was deemed to be the 'wrong' material.
The pair missed up to three days of lessons due to the short skirts row.
Now the mums of Mia Bentley and Olivia Johnson, both 12, say they are disgusted by the school's stern actions, saying the 'punishment doesn't fit the crime'.
Alyson Bentley, 40, told her local paper: "I'm absolutely disgusted that Mia has had to be off school for three days over this. It's just so petty and a really bad way of dealing with the issue.
"As far as I'm concerned the skirt is the required length but they say it rides up when she was walks or goes up the stairs - but all clothes can do that in those circumstances.
"Whatever you're wearing your trousers or jeans or skirts will ride up when you sit down or move - you can't help that. That's no reason to make a girl miss three days of school.
"Mia has tried other skirts but they are too long and too big. Sending them home is not right. Surely a detention or a warning would be more appropriate."
The year 8 pupils are now so upset over the affair that their parents are considering transferring them to different schools.
Olivia's mother Deborah Jobson, 41, said: "It's ludicrous. The girls have basically been sent home for simply following the rules. The skirts are quite clearly knee-length - I don't know who says which part of the knee it has to be.
"The school policy states knee-length black skirt and that's what this is. The policy has always been there and there's never been a problem until now.
"The punishment doesn't fit the crime. It's not proportionate. The girls have missed out on vital learning.
"People are saying we should follow the rules for our daughters but we are... It's atrocious the school will go to such lengths over a skirt not to mention the time it took me to actually speak to someone about it.
"Mia and Olivia are both good kids. Olivia had an outstanding school report yet the staff seem happy to put them through all this and allow them to miss days.
Waterhead Academy's community director Alison Taylor said school policy was for either parents to bring alternative uniform into school or pupils would be sent home.
She added: "All parents and students are aware of the Academy's uniform policy.
"It is the responsibility of parents to send their children to school appropriately dressed. Students and parents are given an opportunity to resolve issues with uniform should they arise."