In this research, the extracts obtained from various natural products (hazelnut shells, thyme, olive shoots, and walnut leaves), which are indicated to have antioxidative characteristics, which are used during the retanning stage of leather manufacturing and their effects on chromium(VI) formation in leather was examined. Finished leathers were exposed to ageing conditions for 24h at 80^oC and for 24h and 72h at 80^oC under UV in order to enable chromium(VI) formation in the leathers. Chromium(VI) amounts in each leather sample were measured with a Shimadzu UV-1601 PC UV-Visible spectrophotometer at 540 nm according to the ISO/FDIS 17075 standard method, and how each extract affected chromium(VI) formation in leather was examined. According to the findings of the research; Coridothymus capitatus, Olea europaea, Corylus avellana, and Juglans regia extracts, which were used during the retanning stage of leather manufacturing, significantly reduced chromium(VI) formation in the leather under all three ageing conditions. The best reduction was obtained with Coridothymus capitatus extract in the ratio of 89.24% under the ageing condition of 24h/80^oC. It is recommended that different extraction methods, different natural extracts, and different ageing conditions be carried out in the future are to optimize the results of the current study.