This preliminary study aimed to analyse the roll-off of the foot during gait before and after implantation of a unilateral pallidal electrode in severely affected patients with Parkinson's disease (PD). Five subjects were tested in a gait laboratory during the "on" phase of the medication cycle. Spatiotemporal variables demonstrated a pronounced increase of stride length and gait speed in three patients. Plantar force distribution and roll-off was considerably improved in one patient, which was not replicated in others. Gait analysis highlighted the variable effects found after surgery with a pallidal stimulator and might contribute to future studies into the effect of surgical procedures in PD.