  The recent progress in the investigations on the quark structure of the
$\Lambda$ and $\Sigma$ baryons are reviewed. It is shown that the quark
structure of $\Lambda$ and $\Sigma$ hyperons can provide a new domain to test
various theories concerning the spin and flavor structure of the nucleon. The
$\Lambda$ and $\Sigma$ Physics might be new directions to explore the quark
distributions of baryons both theoretically and experimentally.
