Dayak women in Borneo treat their skin with natural ingredients, one of which is taya cortex (Nauclea subdita). Flavonoids that can be found in natural ingredients have antioxidant effect and can inhibit the activity of tyrosinase in melanogenesis process. The research objectives were to measure the antioxidant activity and the inhibition of tyrosinase of taya cortex extract, to obtain a stable formulation of taya cortex extract gel, and to determine the safety and efficacy on human skin. The method used for antioxidant activity test was DPPH method. The inhibition of tyrosinase was conducted with kojic acid as control. The safety and efficacy test were conducted to healthy women ages 35-50 with healthy and normal skin. The results show IC50 value of 568.58 µg/mL in L-tyrosine and 1374.69 µg/mL in L-DOPA for inhibiton of tyrosinase. Antioxidant activity assay of the extract shows IC50 value of 48.78 µg/mL and can be categorized as a powerful antioxidant (<50 µg/mL). The formulation of gel containing taya cortex extract was physically stable for 12 weeks. Safety test and efficacy test of the gel show the gel is safe to use topically and show an increase in skin elasticity.