  We investigate the possible regular solutions of the boundary Yang-Baxter
equation for the vertex models associated with the $C_{n}^{(1)}$, $D_{n}^{(1)}$
and $A_{2n-1}^{(2)}$ affine Lie algebras. We find three types of solutions with
$n$, $n-1$ and 1 free parameters,respectively. Special cases and all diagonal
solutions are presented separately.
