Abstract: A tool changer mechanism for a vertical spindle machining center has a remotely positioned tool storage magazine. Tools are transferred between the magazine and the spindle by a tool transfer assembly which is mounted for reciprocating sliding movement along the side of the machining center. The tool transfer assembly incorporates a pivotally mounted support adapted for vertical movement and a rotatable transfer arm, having two grippers, carried by the support. During reciprocating movement of the tool transfer assembly, the support undergoes a pivoting movement with respect to the assembly while the angular position of the arm with respect to the support remains fixed. As the tool transfer assembly reaches the end of its movement toward the spindle, an empty gripper secures the old tool. The support is then lowered so that the arm may be rotated to place a new tool in the other gripper in alignment with the spindle. When the support is raised, the new tool is inserted in the spindle.