  The problem of describing the boundary states of unstable non-BPS D-branes of
type-II string theories in light-cone Green-Schwarz (GS) formalism is
addressed. Regarding the type II theories in light-cone gauge as different
realizations of the $\hat{SO}(8)_{k=1}$ Kac-Moody algebra, the non-BPS D-brane
boundary states of these theories are given in terms of the relevant Ishibashi
states constructed in this current algebra. Using the expressions for the
current modes in terms of the GS variables it is straightforward to reexress
the boundary states in the GS formalism. The problem that remains is the lack
of manifest SO(8) covariance in these expressions. We also derive the various
known expressions for the BPS and non-BPS D-brane boundary states by starting
with the current algebra Ishibashi states.
