This chapter describes the most bioactive compounds extracted from celery (Apium graveolens L.) leaves. Therefore, there are many bioactive compounds such as polyphenols, volatile organic compounds, dietary fibers, and essential oils. Besides, celery has a characteristic taste and smell due to the content of volatile compounds, i.e., terpenes, aldehydes, and phthalides. Moreover, celery leaves possess many clinical activities such as antioxidant, anti-inflammatory, and antibacterial. Therefore, the results indicated that celery, thanks to its content of numerous biologically active substances, is important in health care and can have positive effects on endocrine disorders.