<<Disclaimer: Verify this information before applying it to your situation.>> Buckwheat, Fagopyrum esculentum, is an herb belonging to the family Polygonaceae and is not, as popularly believed, a cereal grain. Everything I have ever read about it has stated that it contains no gluten. Perhaps you were looking at a product such as a buckwheat pancake mix as they often combine buckwheat flour with a gluten containing flour. I would be very surprised if a box of pure buckwheat said it contains gluten.