Mentha aquatica Linn. var. crispa is commonly used as a spice in many Asian countries. Although its biological activities, such as its applications, antimicrobial properties, have been studied, its antioxidation properties have not been investigated. This study establishes the most suitable extraction conditions concerning the independent variables affecting the total polyphenol content (TPC) and antioxidant activity (AA) of M. aquatica extract (stem and leaf). Investigated factors include the type of solvent used; solvent concentration, the ratio of raw material to solvent, extraction time and extraction temperature. The efficiency of polyphenol extraction was evaluated by TPC and AA through the ability to neutralize the free radicals 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS), and the ferric reducing antioxidant power (FRAP) was used as the evaluation indicator. The results have shown that acetone at a concentration of 50%, at a ratio of 1:20 (w/v), extraction time of 2 h and a temperature of 40 °C give the highest values of TPC and AA, with values of 120.92 mg GAE g-1 dw for TPC, 169.36 μmol TE g-1 dw by DPPH assay, 264.03 μmol by ABTS assay, and 425.35 μmol Fe2+ g-1 dw by FRAP assay. This study demonstrates that extracts of M. aquatica can be used for research as food antioxidant.