SummaryThis paper reviews the current status of diagnostic and surgical arthroscopy in the horse. Arthroscopy has been used as a diagnostic aid since 1974 and is useful for evaluation of abnormalities in synovial membrane and articular cartilage. Surgical arthroscopy is a more recent advance that has replaced conventional arthrotomy in 90 per cent of the author's cases. Clinical conditions currently being treated using arthroscopic techniques rather than arthrotomy include all chip fractures in the carpus, chip fractures of the first phalanx, chronic proliferative synovitis in the fetlock and osteochondritis dissecans of the femoropatellar and tibiotarsal joints. The equipment requirements and basic techniques are reviewed. Convalescent time following surgery is decreased and the cosmetic appearance improved compared to arthrotomy. Considerable experience is required for competent surgery which, in turn, is necessary for this method to have advantage over previous conventional techniques.