Pseudogout is a term named in 1962 by McCarty to describe calcium pyrophosphate deposition in and around joint, and a variety of names have been linked to this condition as calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, chondrocalcinosis, articular and periarticular calcification, pyrophosphate arthropathy etc. Clinical features of the pseudogout are similar to a variety of other conditions, including gout, rheumatoid arthritis, degenerative joint disease, and neuroarthropathy. Demonstration of either CPPD crystal deposition by polarized light microscopy and chondrocalcinosis or CPPD crystal deposition by definitive means (X-ray diffraction powder pattern) is required for definitive diagnosis, and it is important to diHerentiate this condition with other disease associated with CPPD crystal deposition. We are reporting a 72-year-old man, suspected to be chondrocalcinosis on the plain radiographs and classified into pseudogout, was studied by arthroscopy, tissue pathology and scanning electromicroscope (SEM) for crystal detection and identification, and had dramatic relief of pain after arthroscopic synovectomy and lavage accompanied by NSAID medication.