The prevalence of radiation synovectomy practice is unknown. As new particulate radiopharmaceuticals offering many potential advantages are being developed, it seems prudent to appraise the extent, frequency and variation in radiation synovectomy practice. We have evaluated radiation synovectomy practice in Europe over the period 1991-1993 by means of a postal questionnaire. More than 2300 European members of the European Association of Nuclear Medicine were questioned about the number of treated patients and joints, disease prevalence in their patients and the use of radiopharmaceuticals. Overall, 119/490 (24%) of centres replying to the survey practised radiation synovectomy during the 3 years. There were 13,450 different joint injections in 8578 patients. Rheumatoid arthritis was the most prevalent disease in patients treated (71%) and the most frequently treated joints were knee (46%) and finger joints (20%). Eight different radiopharmaceuticals were employed. Yttrium-90 colloids were most frequently and widely (100/119 centres) used, mainly employed for knee synovectomy but were also used to treat most appendicular joints. Erbium-169 colloid was almost exclusively used to treat finger joints (31/33 centres). Corticosteroid was routinely co-injected in 36/60 (60%) centres. Radiation synovectomy was widely practised throughout Europe during 1991-1993. There are variations in practice illustrated by the diversity of treated arthritides and injected joints and by the use and application of different radiopharmaceuticals.