Not all protein bars are gluten-free. Whether a protein bar is gluten-free or not depends entirely on the ingredients used by the manufacturer. Some brands do specifically offer gluten-free protein bars, such as RXBAR or Larabar, but many others may include wheat-based ingredients or be at risk for gluten cross-contamination during production. Always check the product label if you have celiac disease or a gluten intolerance, and look for packages that specifically state the bars are gluten-free.