OBJECTIVE To develop a technique for standing diagnostic needle arthroscopy of the radiocarpal and middle carpal joints in standing sedated horses. METHODS Experimental study. METHODS Six cadaveric forelimbs (phase 1) and six healthy horses (phase 2). METHODS In phase 1, six cadaveric forelimbs were used to assess needle arthroscopic evaluation of both joints. Six healthy horses were subsequently enrolled in phase 2 to validate the procedure in live animals. The joint was maintained in flexion with a custom-made splint and base. RESULTS In phase 1, needle arthroscopy allowed thorough evaluation of the dorsal and palmar recesses of both joints with traditional arthroscopic portals. In phase 2, joint evaluation was also thorough but only dorsal approaches were performed. All horses underwent radiocarpal joint arthroscopy, whereas the middle carpal joint was evaluated in only three of six horses because of limb movement. The technique was quickly performed and well tolerated by all horses. Complications included moderate movement, mild iatrogenic cartilage damage, and mild hemarthrosis. CONCLUSIONS Standing needle arthroscopy allowed thorough evaluation of the dorsal aspect of both joints, although only three of six middle carpal joints were assessed because of movement limitations. CONCLUSIONS The proposed technique offers an alternative diagnostic tool for radiographically silent intra-articular lesions of the carpus while initially avoiding the cost and risks associated with general anesthesia. Arthroscopy of a single joint is recommended to minimize risks associated with movement during the procedure.