Abstract: An apparatus for comminuting homogeneous or autogeneous bone fragments into substantially homogeneous particles for use in bone grafting wherein a housing is provided having separate compartments for a motor and a comminuter driven by the motor. A chute and ram are provided to feed bone fragments into contact with the comminuter and the comminuted particles are collected in a removable tray. The compartment housing the comminuter may be readily disassembled for cleaning and, when so disassembled, the motor is vented to atmosphere to prevent operation. The resultant comminuter bone particles are collected in a removable tray below the comminuter.