Inclusion Criteria: - On hemodialysis for at least 3 months and have received intravenous vitamin D therapy (paricalcitol or doxercalciferol) for at least 3 months prior to entering screening - Historical iPTH 150-800 pg/ml (or biPTH 80-430 pg/ml) within 6 months and corrected serum Ca greater than 8.4 mg/dl within 2 months prior to screening period. For subjects with biPTH 80-160 pg/ml (iPTH 150-300 pg/ml), Ca x P must be greater than 55 mg²/dl² within 2 months prior to the screening period - Screening (pre-washout) biPTH 80-430 pg/ml and a corrected serum Ca level greater than 8.4 mg/dl. For subjects with biPTH 80-160 pg/ml Ca x P must be also greater than 55 mg²/dl² - Baseline mean biPTH (post-washout) greater than 160 pg/ml and mean corrected Ca greater than 8.4 mg/dl Exclusion Criteria: - Parathyroidectomy in the 3 month period prior to screening - Current gastrointestinal disorder that may be associated with impaired absorption of orally administered medications or an inability to swallow tablets - Use of investigational drug or device or participation in a trial of investigational drug or device within 30 days of screening - Females of child bearing potential who are pregnant (e.g., positive pregnancy test) or are breast feeding or who refuse to use highly effective contraceptive measures (as determined by the investigator) throughout the study - Previously participated in this or any other Sensipar® study or has received or is receiving Sensipar® as a commercially available product