The lawsuit was filed Friday in Oktibbeha County Circuit Court against the Starkville School District.
Attorney Daniel Tucker, of Booneville, says the lawsuit was accompanied by affidavits from parents, students and other residents.
Named as defendants are the school board and Superintendent Judy Couey.
No hearing date has been set.
The school board approved the dress code earlier this month. The code specifies the types of shirts, pants and other clothing students will be allowed to wear. Each school would determine clothing colors.