In a large bowl, whisk together the flour, oat bran, baking powder, salt, and sugar. Cut in butter until the mixture resembles coarse meal. Gradually stir in milk until dough pulls away from the side of the bowl.
Turn out onto a floured surface, and knead and fold about 10 times. Pat or roll dough out to 1 inch thick. Cut biscuits with a cutter or juice glass dipped in flour. Repeat until all dough is used. Brush off the excess flour, and place biscuits onto an ungreased baking sheet.
Bake for 13 to 15 minutes in the preheated oven, or until edges begin to brown.