A concealed guide rail assembly includes runner carriages which are guided on each side of a drawer between a respective supporting rail on the side of a furniture body and a pull-out rail on the side of the drawer. The supporting rails have an upwardly open U-shaped profile with horizontally extending marginal flanges. Rollers of the runner carriages move on the upper side as well as on the lower side of the supporting rails, i.e. in the U-shaped profile and at the marginal flanges.
