Curcuma longa (turmeric) extract is known to have good and stable antioxidant properties. Therefore, this study aims to determine the antioxidant activity of the turmeric extract towards the inhibition of trans fatty acids formation in repeatedly heated cooking oil (RCO). This experimental research was conducted through several procedures, including maceration to obtain the turmeric extract, which was subsequently added to the RCO resulting from 1, 5, and 10 frying times. In addition, the extraction of oil absorbed in fried food was also performed, followed by contents analysis of trans fatty acids. The results showed the potential application of turmeric extract as an antioxidant, due to the high IC50 value of 12.38μg/mL, alongside 21.85% free radicals suppressing activity in cooking oils