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Two problems are discussed here. The first one is the 0.4 dex discrepancybetween the 7Li abundance derived from the spectra of metal-poor halo stars onthe one hand, and from Big Bang nucleosynthesis, based on the cosmologicalparameters constrained by the WMAP measurements, on the other hand. Lithium,indeed, can be depleted in the convection zone of unevolved stars. Theunderstanding of the hydrodynamics of the crucial zone near the bottom of theconvective envelope in dwarfs or turn-off stars of solar metallicity hasrecently made enormous progress with the inclusion of internal gravity waves.However, similar work for metal-poor stars is still lacking. Therefore it isnot yet clear whether the depletion occurring in the metal-poor starsthemselves is adequate to produce a 7Li plateau. The second problem pertains tothe large amount of 6Li recently found in metal-poor halo stars. Theconvection-related asymmetry of the 7Li line could mimic the signal attributedso far to the weak blend of 6Li in the red wing of the 7Li line. Theoreticalcomputations show that the signal generated by the asymmetry of 7Li is 2.0,2.1, and 3.7 per cent for [Fe/H]= -3.0, -2.0, -1.0, respectively (Teff =6250 Kand log g=4.0 [cgs]). In addition we re-investigate the statistical propertiesof the 6Li plateau and show that previous analyses were biased. Our conclusionis that the 6Li plateau can be reinterpreted in terms of intrinsic lineasymmetry, without the need to invoke a contribution of 6Li. (abridged)

Overview of the lithium problem in metal-poor stars and new results on 6Li