For the approval of cinacalcet hydrochloride, five clinical trials have been performed excluding pharmacokinetic studies for healthy volunteers and hemodialysis patients. An early phase II dose-finding study was started for regular hemodialysis patients with secondary hyperparathyroidism from a daily dose of 12.5 mg cinacalcet and increasing 25 mg up to 50 mg for 9 weeks. A placebo-controlled double-blind three dose-finding study (late phase II study) was then conducted. By this trial, an adequate initial dose of cinacalcet was determined as 25 mg daily, and the placebo-controlled double-blind study (phase III study) was started using this initial dose. Two long-term (1 year) phase III open trials were also conducted during and after these phase II and III studies. The results of two double-blind trials (phase II and phase III) and safety profiles of cinacalcet in all Japanese clinical trials for approval are summarized in this article.