A clamping mechanism for a food slicing machine having a product holder that is driven cyclically through a food slicing blade along an arcuate or linear path. The clamping mechanism is driven by the drive means that drives the product holder, thereby assuring the timing of the clamping during the cutting portion of the stroke. A drive rod extends from the drive means, which can be a driveshaft, and extends to a plate that is pivotably mounted to the product holder. The plate pushes plungers through the sidewall of the holder to seat against and clamp the food product against the sidewall of the holder.