A new cultivar of Hosta named `Roy Klehm`, a chemically induced chimeral mutation of Hosta `Summer Serenade`, that is characterized by its unique variegated foliage with bright yellow-green centers and wide deep green margins comprising about one half of the leaf area. `Roy Klehm` has an upright plant habit with leaves held horizontal on upright petioles and near white flowers held on erect flower scapes that arise above the foliage in mid summer.