The transport equation in slab geometry is solved by means of the DPN “surface flux” method, based on a Pn polynomial expansion in both angle and space and a double Pn approximation of the angular distribution at interval surfaces. The method, which has been incorporated into the multigroup transport code SURCU, is compared to a number of different codes such as ANISN, DIT, etc. For a given accuracy in the flux SURCU turns out to be faster than other codes since it needs fewer spatial flux moments than other programs need regions or space points. In addition, the required DPN surface flux approximation is much lower than the corresponding Sn approximation. A number of similarities between the present method and both Sn theory and collision probabilities are discussed.