If arthroscopy is indicated the doctor should inform the patient in detail about the intended procedure. The investigation is normally carried out on an ambulatory basis. If there are reasonable grounds for suspecting the presence of a lesion which requires surgery it is advisable to discuss the possibility of an immediate operation with the patient directly following arthroscopy. A few days before the investigation the patient is sent a letter telling him the date and time of his appointment and whether the procedure is to be carried out under general or local anaesthesia. In both cases we ask the patient to fast on the morning of the investigation. The patient can also simplify the pre-operative preparations by shaving the skin around his knee joint.