This study aims to investigate the effect of across mass transfer (AMT) phenomenon on a three-dimensional steady viscous flow in a channel of lower stretching wall. The phenomenon of AMT is established by imposing suction at one plate and injection at the other plate of the channel simultaneously. Both the walls are assumed to be porous so that suction/injection can take place. Interesting observations regarding viscous drag at the stretching plate have been recorded in the presence of AMT phenomenon at the twin walls. A highly accurate purely analytic solution has been obtained for the governing nonlinear equations. The issue of convergence and accuracy of the analytic solution has been discussed in detail. Results are discussed through graphs.