For the most part canned cream of mushroom soups are not gluten free because they have wheat flour in them. Wheat contains gluten. Many companies use wheat flour as a thickening agent in the soups. If you want gluten free cream of mushroom soup the best solution is to make it yourself. You can always buy one of the brands that sell gluten free cream of mushroom soup which include: Progresso Cream of Mushroom Soup, Imagine Food's Portobello Mushroom Creamy Soup, Pacific Food's Organic Cream Of Mushroom Condensed Soup.