An electrosurgical instrument (10; 1000) for treating tissue, comprising: a housing (20; 1020) having a shaft (12; 1012) extending therefrom having an axis A-A defined therethrough, the shaft (12; 1012) being at least partially flexible and including first and second jaw members (110, 120; 1110, 1120) attached at a distal end thereof, each jaw member (110, 120; 1110, 1120) including an electrically conductive tissue contacting surface (112, 122; 1112, 1122) adapted to connect to a source of electrosurgical energy such that the electrically conductive tissue contacting surfaces (112, 122; 1112, 1122) are capable of conducting electrosurgical energy through tissue held therebetween; a drive assembly (150; 1700) disposed in the housing and including a first actuator operably coupled to a flexible drive rod (142; 1142) for reciprocation thereof and a second actuator operably coupled to the flexible drive rod for rotation thereof, wherein actuation of the first actuator reciprocates the drive rod (142; 1142) which, in turn, moves the first and second jaw members (110, 120; 1110, 1120) from a first position in spaced relation to one another to a second position closer to one another for engaging tissue; a knife operably coupled to a distal portion of the drive rod, wherein actuation of the second actuator rotates the drive rod about the axis A-A to translate the knife relative to the jaw members; and a third actuator disposed on the housing (20; 1020) and actuatable to articulate a flexible portion of the shaft, the flexible portion of the shaft including a plurality of joints (12a; 1312) nestingly arranged in series, the third actuator including an articulation assembly having at least one actuatable component (1090a, 1090b) disposed on the housing operably coupled to a pulley system (1610a, 1610b) for reciprocating articulation cables (1094a, 1094b) through the shaft to articulate the shaft to effect movement of the first and second jaw members between an axially aligned condition wherein the first and second jaw members are aligned with the axis A-A, and an articulated condition wherein the first and second jaw members (110, 120; 1110, 1120) are displaced in a direction transverse to the axis A-A. a housing (20; 1020) having a shaft (12; 1012) extending therefrom having an axis A-A defined therethrough, the shaft (12; 1012) being at least partially flexible and including first and second jaw members (110, 120; 1110, 1120) attached at a distal end thereof, each jaw member (110, 120; 1110, 1120) including an electrically conductive tissue contacting surface (112, 122; 1112, 1122) adapted to connect to a source of electrosurgical energy such that the electrically conductive tissue contacting surfaces (112, 122; 1112, 1122) are capable of conducting electrosurgical energy through tissue held therebetween; a drive assembly (150; 1700) disposed in the housing and including a first actuator operably coupled to a flexible drive rod (142; 1142) for reciprocation thereof and a second actuator operably coupled to the flexible drive rod for rotation thereof, wherein actuation of the first actuator reciprocates the drive rod (142; 1142) which, in turn, moves the first and second jaw members (110, 120; 1110, 1120) from a first position in spaced relation to one another to a second position closer to one another for engaging tissue; a knife operably coupled to a distal portion of the drive rod, wherein actuation of the second actuator rotates the drive rod about the axis A-A to translate the knife relative to the jaw members; and a third actuator disposed on the housing (20; 1020) and actuatable to articulate a flexible portion of the shaft, the flexible portion of the shaft including a plurality of joints (12a; 1312) nestingly arranged in series, the third actuator including an articulation assembly having at least one actuatable component (1090a, 1090b) disposed on the housing operably coupled to a pulley system (1610a, 1610b) for reciprocating articulation cables (1094a, 1094b) through the shaft to articulate the shaft to effect movement of the first and second jaw members between an axially aligned condition wherein the first and second jaw members are aligned with the axis A-A, and an articulated condition wherein the first and second jaw members (110, 120; 1110, 1120) are displaced in a direction transverse to the axis A-A.