Galactic evolution of D and 3He

The most recent chemical evolution models for D and He-3 are reviewed and their results compared with the available data. Models in agreement with the major galactic observation al constraints predict deuterium depletion from the Big Bang to the present epoch smaller than a factor 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 galaxy (e.g. SFR, abundances, abundance ratios and/or gradients of heavier elements, metallicity distribution of G-dwarfs). Observational and theoretical He-3 abundances can be reconciled with each other if the majority 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-hydrogen burning.