Background: The role of joint mechanoreceptors is not fully understood to date. The findings of mechanoreceptors from different joints and mammals have been described for decades. However, most of the studies were performed in silver or gold chloride stains, which was criticized for non-specificity. The conventional observations projected three-dimensional structures onto two-dimensional pictures, which misinterpret a true image of mechanoreceptors. Immunohistochemistry and confocal laser scanning microscopy is a powerful tool to observe nerve endings specifically and three dimensionally, which has been applied in the studies of Meissner corpuscles and revealed excellent results. The technique was attempted in morphological study of mechanoreceptors on the radiocarpal joint. Materials and Methods: The ligaments of radiocarpal joint, including dorsal radiocarpal, radioscaphocapitate, long radiolunate, radioscapholunate and short radiolunate ligaments, were gathered from four fresh cadavers within 12 hours of death. Fluoroscopy was performed to exclude any arthritic conditions of the wrists. Tissues were fixed, sectioned, and serially collected on glass slides. Slides were processed for fluorescence immunohistochemistry using antibody to protein gene product 9.5 (PGP 9.5) and a secondary antibody conjugated to a fluorescent tag, Alexa Fluor 488. The sections were observed with a confocal laser scanning microscope (LSM-510, Carl Zeiss Inc.). Labeled mechanoreceptors were pictured, saved and reconstructed three-dimensionally. Results: Our immunohistochemistry protocol offers constant staining of all nerve tissues for analyzing. Through confocal laser scanning microscopy, z-serial optical sections of mechanoreceptors could be reconstructed three-dimensionally and manipulated for observations from different angles. Four major types of mechanoreceptors were identified in ligaments from radiocarpal joint. Ruffini-like receptors were fusiform or discoid in shape and measured from 60 to 450ìm in maximum dimension. Pacinian-like receptors were discoid in shape and measured 90 to 130ìm. Golgi-like receptors were generally spindle or cylindrical in shape. The maximum dimension was between 400 and 720ìm. Free nerve endings were identified either as single strands or ramifying arborizations. The terminal fibers were from 1.0 to 1.5ìm in diameter. Other than these four major categories, there were some nerve endings recognized as unclassifiable. Discussion: Immunohistochemistry and confocal laser scanning microscopy provide a renewed recognition of joint mechanoreceptors. The strength of this technique are (1) specific staining of all nerve tissues, (2) high resolution of images and (3) advanced analysis through manipulation of 3-D images. The current limitation is to stack 3-D images of mechanoreceptors across adjacent slides. Further improvement of processing technique will be necessary for stereo observation and measurement.