GALACTIC EVOLUTION OF D AND HE-3

The most recent chemical evolution models for D and He-3 are reviewed and their results compared with the available data. Models in agreemen t with the major galactic observation al constraints predict deuterium depletion from the Big Bang to the present epoch smaller than a facto r of 3 and therefore do not allow for D/H primordial abundances larger than similar to 5 x 10(-5). Models predicting higher D consumption do not seem to be able to reproduce other observed features of our galax y (e.g. SFR, abundances, abundance ratios and/or gradients of heavier elements, metallicity distribution of G-dwarfs). Observational and the oretical He-3 abundances can be reconciled with each other if the majo rity of low mass stars experience in the red giant phase a deep mixing allowing the consumption of most of the He-3 produced during core-hyd rogen burning.