An electromechanical surgical system, comprising: a shaft assembly; a hand-held surgical instrument including an instrument housing defining a connecting portion for selectively connecting with the shaft assembly, the surgical instrument having at least one rotatable drive member (118, 120, 122); an end effector configured to perform at least one function; the end effector being one of a plurality of user selectable end effectors, characterized in that the shaft assembly is arranged for user selectively interconnecting the user selected end effector and the surgical instrument, the shaft assembly including: a transmission housing configured and adapted for user selective connection to the connecting portion of the surgical instrument and to be in operative communication with each of the at least one rotatable drive member of the surgical device; an outer tubular body having a proximal end supported by the transmission housing and a distal end configured and adapted for operative connection with the end effector; a force transmitting assembly (228, 246a, 258a) for interconnecting a respective one of the at least one rotatable drive member of the surgical instrument and at least one rotation receiving member supported in the end effector, wherein the force transmitting assembly includes a first end that is user connectable to the at least one rotatable drive member of the surgical instrument and a second end that is user connectable to the at least one rotation receiving member of the end effector, wherein the force transmitting assembly transmits a rotation of the at least one rotatable drive member of the surgical instrument to the at least one rotation receiving member of the end effector. a shaft assembly; a hand-held surgical instrument including an instrument housing defining a connecting portion for selectively connecting with the shaft assembly, the surgical instrument having at least one rotatable drive member (118, 120, 122); an end effector configured to perform at least one function; the end effector being one of a plurality of user selectable end effectors, characterized in that the shaft assembly is arranged for user selectively interconnecting the user selected end effector and the surgical instrument, the shaft assembly including: a transmission housing configured and adapted for user selective connection to the connecting portion of the surgical instrument and to be in operative communication with each of the at least one rotatable drive member of the surgical device; an outer tubular body having a proximal end supported by the transmission housing and a distal end configured and adapted for operative connection with the end effector; a force transmitting assembly (228, 246a, 258a) for interconnecting a respective one of the at least one rotatable drive member of the surgical instrument and at least one rotation receiving member supported in the end effector, wherein the force transmitting assembly includes a first end that is user connectable to the at least one rotatable drive member of the surgical instrument and a second end that is user connectable to the at least one rotation receiving member of the end effector, wherein the force transmitting assembly transmits a rotation of the at least one rotatable drive member of the surgical instrument to the at least one rotation receiving member of the end effector. a transmission housing configured and adapted for user selective connection to the connecting portion of the surgical instrument and to be in operative communication with each of the at least one rotatable drive member of the surgical device; an outer tubular body having a proximal end supported by the transmission housing and a distal end configured and adapted for operative connection with the end effector; a force transmitting assembly (228, 246a, 258a) for interconnecting a respective one of the at least one rotatable drive member of the surgical instrument and at least one rotation receiving member supported in the end effector, wherein the force transmitting assembly includes a first end that is user connectable to the at least one rotatable drive member of the surgical instrument and a second end that is user connectable to the at least one rotation receiving member of the end effector, wherein the force transmitting assembly transmits a rotation of the at least one rotatable drive member of the surgical instrument to the at least one rotation receiving member of the end effector.