  We use a diagrammatic approach to study low energy physics of a two
dimensional electron system where the Fermi level is near van-Hove singularies
in the energy spectrum. We find that in most regions of the $\epsilon_F-T$
phase diagram the system behaves as a normal Fermi liquid rather than a
marginal Fermi liquid. Particularly, the imaginary part of the self energy is
much smaller than the excitation energy, which implies well defined
quasiparticle excitations, and single particle properties are only weakly
affected by the presence of the van-Hove singularities. The relevance to high
temperature superconductivity is also discussed.
