This book reviews the major components of synovial fluid analysis, with an emphasis on crystal recognition. Synovial fluid analysis is the required gold standard test for the definitive diagnosis of septic and crystal induced arthritis, the most frequent causes of acute inflammatory arthritis. Synovial fluid is obtained routinely from patients with acute arthritis by clinicians in many specialties. Fluids are sent to the clinical pathology and microbiology laboratories for analysis, but are also frequently examined directly by rheumatologists and others for the presence of crystals. Competency in synovial fluid crystal analysis is a requirement for all graduating rheumatology fellows in the United States, and is an expectation for musculoskeletal disease physicians internationally   although competency is assumed with a variable degree of rigor.