384 patients were subjected to arthroscopy in 1980 and 1981. Pathological findings were obtained in 361 patients, mainly lesions of the meniscus. In 51 patients (approx. 14% of the cases) arthrotomy became necessary for various reasons. 310 patients were subjected to surgery, using the arthroscope. Follow-up examinations showed that the postoperative healing phase and hence also the postoperative inpatient period were significantly reduced compared with those patients who had been subjected to arthrotomy with the same therapeutic effect. Patients who have undergone arthroscopy re-attain their full knee-joint function much earlier than those on whom arthrotomy was performed. Hence, their ability to work is restored more quickly, and they are much sooner able to resume their sports activities.