Abstract: A modular medical instrument is used with an endoscope or other similar medical instrument to perform medical procedures, such as endoscopy, bronchoscopy, and laparoscopy. The modular medical instrument comprises an elongated instrument device, an optional port fitting detachably coupled to the instrument device, and an actuator handle detachably coupled to the port fitting. The instrument device includes an elongated guide member, an inner actuation cable slidably disposed within the guide member, and an instrument device head assembly disposed at a distal end of the guide member and actuation cable. The guide member preferably has a smooth outer surface to facilitate insertion within the instrument channel of an endoscope or similar medical device. In one example, the instrument device head assembly includes a grasping device, such as biopsy forceps.