Seyval blanc (; or Seyve-Villard hybrid number 5276) is a hybrid wine grape variety used to make white wines. Its vines ripen early, are productive and are suited to fairly cool climates. the United States East Coast (specifically the Finger Lakes region of upstate New York, Lake Erie AVA in Pennsylvania,), as well as to a lesser extent in Canada. and was used to create the hybrid grape St. Pepin. Seyve and Villard used the same Rayon d'Or x Seibel 5656 crossing to produce the red wine grape Seyval noir.
Since it contains some non-vinifera genes, Seyval blanc is outlawed by the EU authorities for quality wine production, which was an issue of conflict with the English wine industry.