An instrument for clamping and trimming the bone tendon portion of a graft to a desired size, comprising a pair of elongated handles each having jaws at one end; the handles being hinged together at a pivot point allowing the jaws to open and close in a scissor arrangement, the jaws defining a generally U-shaped trapezoidal receptacle when the jaws are closed about the bone tendon portion of the graft to be trimmed and the jaws comprising respective upper guide surfaces along their upper edges whereby, when a bone tendon portion is positioned in the U-shaped trapezoidal receptacle, the upper guide surfaces function as a guide for a blade of a saw to trim any excess portion of the bone tendon portion protruding above the upper guide surfaces.