We have formulated a new class of plate-bending equations which simulates the flexure of the lithosphere at mid-ocean ridges. The stress-accumulation effect in a growing (moving and thickening) lithosphere significantly changes the flexural behavior. It is shown that the growing plate flexes more easily than the conventional static plate due to the fact that the bending stress vanishes on the base of the plate. We apply this new plate model to the East Pacific Rise. Compared with Madsen et al. (1984), the fits to the gravity and topography observations are improved. Assuming the thickness varies in proportion to the square-root of distance from the ridge crest, the best fitting thickening rate for the growing plate model is 0.7 (km1/2), or 5.5 km/(m.y.)1/2, which further implies that the 600 or 700¿ C isotherm marks the bottom boundary of the effective elastic thickness of the lithosphere.