The normal coordinates of a nonclassically damped systems are coupled by nonzero off-diagonal elements of modal damping matrix. The relationship between modal coupling and the frequency separation of the natural modes is presented in this paper. Contrary to widely accepted beliefs, increasing the frequency separation of the natural modes does not neccessarily diminish the effect of modal coupling. Consequently, in the pratical engineering applications, wide frequency separation of the natural modes would not be sufficient for neglecting modal coupling.