OBJECTIVE To establish a quality assessment programme for the diagnosis of crystal arthropathies by synovial fluid (SF) microscopy.

RESULTS Returns for the years 1989–1996 were reviewed. Laboratories that participated in > four surveys made on an average one error a year (range 0.25–2). The error rate for specimens containing abundant crystals was acceptable but it increased considerably for specimens showing few crystals per microscope field. No laboratory characteristic predictive of successful performance was found.

CONCLUSION Errors in quality assessment results for crystal identification were much more frequent than in the fields of, for example, clinical chemistry or microbiology. Despite efforts to provide educational feedback, no improvement was seen during the study period. Because of the dearth of data from other parts of the world it is not known for certain whether this study has merely pinpointed a local problem or if the same trend applies elsewhere.