OBJECTIVE: To investigate the changes of calcium in serum and urine after oral administered different brands of calcium supplement in healthy volunteers. METHODS: In a randomized four way crossover study, the serum and urine concentration time profiles were determined after no dosing and po 1 000 mg of calcium single dose of preparation A, B and C. RESULTS: The AUC 0 h～8 h of blank serum, preparation A, B and C were (674.2±49.08)mg·h·L -1 , (728.7±42.47)mg·h·L -1 , (717.5±51.34)mg·h·L -1 , (697.3±52.73)mg·h·L -1 , respectively. The urinary output in 0 h～4 h and 0 h～24 h hours of blank, preparation A, B and C were (13.06±9.88)mg and (65.20±24.97)mg, (34.07±17.67)mg and (138.25±57.35)mg, (34.11±25.97)mg and (147.41±85.79)mg, (25.77±12.49)mg and (99.37±48.20)mg, respectively. CONCLUSION: The statistical analysis for the parameters showed that there was significant difference between each calcium supplement and blank serum or urine (P<0.01), but there was no significant difference between preparation A, B and C (P>0.05).