This study aimed to investigate the in vitro cytotoxic activities of orange peel oil on HaCaT cell lines by using an MTT cytotoxicity assay after administering orange peel oil at different doses and timepoints. Our objective was to assess the in vitro cytotoxic activities of orange peel oil on HaCaT cell lines. Cell viability was determined with the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazoliumbromide] assays