We investigated the pharmacokinetics of 2μg calcitriol in eight healthy human after a single oral administration. Plasma calcitriol was analyzed by sensitive and quantitative enzyme immunoassay following intra- and inter-day validation. In subjects, AUC 0–∞ and AUC 0–24h were 267 and 246pghml −1 , respectively. Although the mean plasma concentration of calcitriol in human subjects did not return to baseline at 24h post-dosing, the mean ratio of AUC 0–24h to AUC 0–∞ was greater than 80%. The C max of calcitriol was measured at 3.4h after administration as 50.0pgml −1 . From our results, it can offer new opportunities to design and determine individually appropriate therapeutic dosage regimens based on a pharmacokinetic profile and be used for bioequivalence and revaluation study of generic drug.