  We discuss the construction of non-chiral S-matrix of four-dimensional N=4
super Yang-Mills using a non-chiral superspace. This construction utilizes the
non-chiral representation of dual superconformal symmetry, which is the natural
representation from the point of view of the six-dimensional parent theory. The
superspace in discussion is projective superspace constructed by Hatsuda and
Siegel, and is based on a half coset U(2,2|4)/U(1,1|2)^2_+. We obtain the
non-chiral representation of the five-point and general n-point MHV and
anti-MHV amplitude. The non-chiral formulation can be straightforwardly lifted
to six dimensions, which is equivalent to massive amplitudes in four
dimensions.
