We examined 36 consecutive patients with closed tibial plateau fractures under anaesthesia and by diagnostic and operative arthroscopy before treating them by closed or open reduction and internal fixation. Following the principle of Hohl (1967) (Fig. 1) there were 9 minimally displaced fractures (type I), 6 with local depression (type II), 13 with split depression (type III), 7 with total condylar depression (type IV), and one bicondylar comminuted upper tibial fracture (type V). Seventeen (47%) of knees were found to have associated meniscal injuries which required surgical treatment; five repairs and 12 partial meniscectomies. Neither the type of plateau fracture nor the presence or absence of ligament injury correlated with meniscal tear. There were no intraoperative or postoperative complications from arthroscopy.