Atomic processes and strengthening effects due to interaction between edge dislocations and voids in α-iron have been investigated by means of molecular dynamics with a recently developed interatomic potential (Ackland et al 2004 ) and compared with those obtained earlier with an older potential (Ackland et al 1997). Differences between the interactions for the two models are insignificant at temperature T 100 K, thereby confirming the validity of the previous results. In particular, voids are relatively strong obstacles because for large voids and/or low temperature, the initially straight edge dislocation is pulled into screw orientation before it breaks away at the critical shear stress, τc. Differences between the core structures and glide planes of the 1/2111 screw dislocation for the two potentials do not affect τc in this temperature range. The only significant difference between the dislocation–void interactions in the two models occurs at low temperature in static or pseudo-static conditions (T 1 K).