Medicinal plants have played an essential part in the discovery and development of medications during the past few decades. Many medicinal plants provide unique treatments with high efficacy and few side effects compared to the known standard pharmaceuticals used to treat the most debilitating diseases, such as cancer. 1 Medicinal plants make up roughly 20% of Jordan's flora. 2,3 As a result, many are used in traditional medicine and pharmaceutical production. 4,5 The Lamiaceae family includes the genus Ajuga as one of its members. Ajuga s a genus of 50 species of evergreen, clump-forming rhizomatous, annual, or perennial herbs that grow to a height of 5-50 cm and are found primarily in Asia, Africa, Australia, and North America, in addition to Europe. 6 Ajuga orientalis L. (also known as Eastern bugle) is a 20-40cm tall annual herbaceous flowering plant with opposite leaves that grows in humid areas (Ajloun, Salt, Amman, and Karak). 2 A. orientalis is a medicinal plant with diverse biological activities. It is used in traditional medicine worldwide to treat rheumatism, gout, diabetes, asthma, malaria, and gastrointestinal disorders. 7,8 A. orientalis has antibacterial, antitumor, antioxidant, and anti-inflammatory properties. [6][7][8][9][10][11] This study aimed to assess the cytotoxic activity of methanolic extract of the aerial part of Ajuga orientalis L. on the human breast cancer cell line (MCF-7).