  We consider the open superstring ending on a D-brane in the presence of a
constant NS-NS B field, using the Green-Schwarz formalism. Quantizing in the
light-cone gauge, we find that the anti-commutation relations for the fermionic
variables of superspace remain unmodified. We also derive the unbroken
supersymmetry algebra living on the D-brane. This establishes how the Moyal
product is extended in a superspace formulation of non-commutative field
theories. The superfield formulation of non-commutative supersymmetric field
theories is briefly considered.
