Percutaneous injection therapy with vitamin D has been applied in the treatment of hyperparathyroidism (HPT); however, the application of percutaneous injection therapy with vitamin D lacks established guidelines regarding the volume of injected solution and the frequency of injection. We have developed an outpatient treatment regimen using percutaneous maxacalcitol injection therapy (PMIT) on a weekly basis for 4-6 weeks following dialysis without major complications. Intact parathyroid hormone decreased from 797 +/- 178 pg/mL to 253 +/- 25 pg/mL, and the parathyroid gland volume initially increased during the first week, but thereafter, it gradually decreased with weekly PMIT (wPMIT). Finally, the parathyroid gland volume decreased from 1.27 +/- 1.06 cm(3) to 0.24 +/- 0.15 cm(3) after wPMIT. The benefits of our method were confirmed on weekly ultrasonographic examinations, which detailed the gradual reduction in gland size following an initial increase after the first injection. Therefore, we conclude that our carefully implemented PMIT method would be an effective treatment against refractory secondary HPT.