Abstract: AIM: To compare several experimental designs for detecting the bioactivity of low-molecularweight heparin (LMWH).METHODS: Chromogenic assay was used for detecting the bio-activity of LMWH by comparing the 4°4 method to 4°3, 3°4 or 3°3 method in quantity response parallel line design.RESULTS: In bioassay of LMWH with the quantity response parallel line analysis, there had no statistical difference (P>0.05) between 4°4 method with 4°3, 3°4 or 3°3 method.CONCLUSION: Quantity response parallel line design could be used in validation of the chromogenic assays for the potency assessment of LMWH.In parallel line design, 4°4, 4°3, 3°4 or 3°3 method of different dose groups all could be used according to the standard for LMWH.

Key words: LMWH, experimentaldesign, biostatistics, bioassay