A transfer unit (100) in an interfolding machine comprises at least a first plurality of separation members (120) carried by a support and handling assembly (130) which moves the above said separation members (120) along a work path (60) comprising a side introduction movement (61) by appropriate constraint members (140, 150, 160) and actuators which comprise electric motors (143, 152, 163) suitable to determine the displacement of the separation members (120) throughout their work path (60) and pneumatic actuators (144, 153, 164) which are of aid to the electric motors (143, 152, 163) exclusively during the side introduction movement (61) which must be performed with very high accelerations and speeds.