Introduction: Previously, we introduced a quantitative electrophysiological method to compare nerve grafts in vitro. This method was used to evaluate the effect of the presence of pores in biodegradable artificial nerve grafts on regeneration. Pores in an artificial nerve graft will allow easier access of nutrients to the regenerating nerve within the graft, and consequently we expected improved regeneration through the porous grafts compared to the non-porous grafts. Methods: Artificial nerve grafts of porous (1-10 µm pore size; n=6) and non-porous (n=6) poly(e-caprolactone) (CL), and of a porous (1-10 µm pore size; n=6) copolymer of trimethylenecarbonate and e-caprolactone (10:90 mol%)(TMC/CL) were used to bridge a 6 mm gap in the rat sciatic nerve. Autografted nerves served as controls. Twelve weeks after surgery, increasing stimulus voltages were applied to the (grafted) sciatic nerve in vitro and the resulting compound action currents were measured. This way the maximum charge displaced (Q_max), the mean conduction velocity (MCV) and the mean voltage threshold (V₅₀) were determined. Results: Q_max measured in the non-porous nerve grafts was too low to be measured in 5 out of 6 regenerated nerves, and was therefore significantly lower compared to the autografts and porous grafts. There were no significant differences in Q_max, MCV and V₅₀ between the two porous grafts. However, in porous grafts Q_max was significantly smaller as compared to the autografted nerves, while MCV and V₅₀ were not significantly different. Of the two porous grafts the TMC/CL graft provided the best surgical handling capability. Discussion: Q_max is mainly determined by the number and by the diameter of the (regenerated) axons. Thus our results indicate that more axons or larger axons or more and larger axons had regenerated through the porous grafts as compared to the non-porous grafts, providing evidence for the beneficial effect of pores in artificial nerve grafts on regeneration. Moreover, though Q_max in the porous grafted nerves was still significantly smaller compared to the autografted nerves, MCV and V₅₀ were comparable. As MCV and V₅₀ are mainly determined by the diameter of the (regenerated) axons, this indicates that the diameter of the regenerated axons in the porous grafts is comparable to the diameter of the regenerated axons in the autografts. Since of the two porous grafts we tested, the TMC/CL graft provided the best surgical handling capabilities, this will be the preferred graft for further experiments.