Modern surgery is looking for ways to carry out procedures which limit unnecessary damage to the patient. This means, in practice, using smaller incisions and special tools. An instrument for removing tissue through a small cross-section has been developed. It is suitable for both endoscopy and laparoscopy. The instrument and its development is described, and its performance evaluated in vitro and for a range of clinical procedures. Experiments aimed at uncovering the mechanism of cutting are discussed as to their relevance for practical instrument development.