2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/7231The temporal behaviour of the radial abundance gradients has important consequences on models for the chemical evolution of the Galaxy. We present a comparison of the time variation of the abundance gradients in the Milky Way disk as determined from a sample of planetary nebulae and open clusters. We conclude that the [Fe/H] gradients as measured in open cluster stars strongly support the time flattening of the abundance gradient as recently determined from O/H measurements in planetary nebulae. We estimate the average flattening rate in the time interval 10 Myr < t < 5 Gyr as roughly 0.005 dex kpc-1 Gyr-1.8 pages, 1 figure, Tex, uses psfig.sty. To appear in Bull. Brazilian Astron. SocAstrophysicstext