Background: The lerak, also known as Sapindus rarak DC, is an industrial plant belonging to the Sapindaceae family, native to Southeast Asia and South Asia. Lerak is a type of plant in Indonesia that grows in lowland areas. Lerak plants are considered to be a highly suitable industrial plant for development. Based on the numerous benefits of lerak plants, it is believed that they contain secondary metabolites that are valuable for the advancement of research and the healthcare industry. Objective: To determine phytochemical screening, characterization and fatty acid compounds of lerak seeds. Methods: The method used in this study was experimental in the laboratory. Phytochemical screening tests alkaloids, glycosides, flavonoids, tannins, saponins, steroids, and triterpenoids. Analysis of fatty acid compounds using gas chromatography. Results: The ethanol extract of lerak seeds was found to contain flavonoids, alkaloids, saponins, tannins, steroids, and triterpenoids. The result of determining the water-soluble essence content of the lerak seed (S. rarak) simplicia was 5.03%, while the ethanol-soluble extract content was 12.19%. The lerak seeds used in this study contained the highest percentage of oleic acid, which was 70.5%, and eicosenoic acid, which was 27.4%. Conclusion: Phytochemical screening lerak seed extract contains secondary metabolites of alkaloids, flavonoids, tannins, saponins, glycosides, steroids, and triterpenoids. The highest fat content contained in lerak seed samples is oleic acid.