Aragonite is one of polymorphs of calcium carbonate of which main form is calcite. We found that white precipitate is formed in much amount by boiling underwater of Inchon, Korea and confirmed that it is aragonite. This study is to evaluate the dimensional characteristics, solubility, acid resistance of aragonite and the cytotoxicity, cell division disturbance and cell transforming ability of it on BALB/3T3 cells. The results are as follows: Lengths of the aragonite were reduced to the 72.7% and 22.7% respectively after 5 months and 7 months of intrapleurai injection to the Sprague-Dawley rat. Strong acid such as 1M HCl dissolved the aragonite instantly but weaker acid pH 2.0 or more could not dissolved aragonite easily. The result of cell growth inhibition showed that cell numbers were decreased as log-doses of treatment of the aragonite were increased 24 hours, 48 hours, and 72 hours later. Cell plating efficiency after the aragonite treatment also showed dose-dependent decrease. Multinuclear giant cell formation was increased in the aragonite treated cells until ID$_{50}$ and after the dose the multinucleate cells were decreased, but remained much higher than negative control cells. Morphological transformation assay showed that the aragonite did not induce transformation in all treated doses.