Progress has been made in electric scalpel technology, as applied to endoscopy, over recent years. Lamp or spark gap scalpels have been replaced by more reliable transistor scalpels fitted with a return electrode avoiding any defective circuits. Before using an electric scalpel, it is essential to understand the basic physical laws governing their use with section, coagulation or mixed currents. Any interference with other electrical apparatuses in the surgical endoscopy room must be avoided and precautions must also be taken in patients with cardiac pacemakers. Different settings are required for colonic polypectomy and endoscopic sphincterotomy in order to ensure a clean cut without oedema and with perfect haemostasis. Although monopolar currents are generally used, some haemostatic or tumour destruction electrodes use a bipolar current which avoids deep necrosis. Diathermy is a precise technique in interventional endoscopy, but surgeons must adapt their knowledge to the equipment used.