Intraarticular observation in the regions where joint spaces are narrow and curved is often difficult. In 1986, an observation method that employs an improved fiberscope inserted intraarticularly was devised for regions where observation with a conventional rigid arthroscope has been difficult. The clinical usefulness of this method was investigated. A total of 45 joints consisting of 11 hip joints, 13 knee joints, and 21 ankle joints were observed by both a rigid arthroscope and a fiberscope, and the findings obtained by the single method and the combined method were compared. The range of visualization was increased by the combined method in 82% of the hip joints, 77% of the knee joints and 62% of the ankle joints, as compared with the single method. Thus the combined method was found to be useful. While the combined method was slightly inferior to the single method of rigid arthroscopy in terms of image resolution, the range of visualization was increased. The combined method is easy to perform and less invasive to the intraarticular structures than the single method, suggesting that the combined method has an important role in intra-articular observation.