['Percutaneous ethanol injection therapy (PEIT) is used for advanced secondary hyperparathyroidism. We investigated the efficacy, remission period and risk of relapse to determine the effect of the number of hyperplastic glands and other factors on the therapeutic effect of PEIT.', 'We studied 321 patients divided into two groups: effective [serum corrected calcium (cCa) level < or =10.5 mg/dl and serum intact parathyroid hormone (iPTH) level < or =250 pg/ml], and ineffective (failed to achieve the target levels). Advanced hyperplasia was defined as an estimated volume > or =0.5 cm(3) on ultrasonography.', 'PEIT was effective in 201 patients (62.6%), in whom serum iPTH levels dropped from 603+/-292 to 183+/-62 pg/ml (ng/l) and serum cCa levels from 10.7+/-0.8 to 10.1+/-0.5 mg/dl. Univariate analysis identified age, the number of hyperplastic glands and iPTH level as factors related to the efficacy of PEIT. The odds ratio for success vs failure by multivariate analysis was 0.55 times for the number of hyperplastic glands > or =0.5 cm(3) (> or =2 vs 0,1) and 0.29 times for iPTH (> or =500 vs <500 pg/ml). Using the Kaplan-Meier method, the number of hyperplastic glands > or =0.5 cm(3) (> or =2 vs 0,1) was a factor affecting the remission period, with a remission significantly longer seen in the group with one hyperplastic gland (P=0.0025).'] Is efficacy of percutaneous ethanol injection therapy ( PEIT ) related to the number of parathyroid glands in haemodialysis patients with secondary hyperparathyroidism?