The spin dependent structure function, g ww 2 , is calculated in the valon model. A simple approach is given for the determination of the twist-3 part of theḡ 2 (x, Q 2 ) in Mellin space; thus, enabling us to obtain the full transverse structure function, g 2 (x, Q 2 ) for proton, neutron and the deuteron. In light of the new data, we have further calculated the transversely polarized structure function of g 3He 2 (x, Q 2 ). Our results are checked against the experimental data and nice agreements are observed.