en Chemotherapy, Antibiotics and Gene Therapy پژوهشي Research Article <div style="text-align: justify;"><em>Trachyspermum copticum</em> is one of the most important Iranian Apiaceae species which is widely distributed in the northern region of Iran. In this study, chemical compounds, anti-tumor and antibacterial activities of <em>T. copticum</em> essential oil were evaluated. The essential oil obtained by Clevenger apparatus and then the chemical composition was analyzed by GC-MS. Antibacterial activity of essential oil was evaluated by well diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by the macrodilution method. An MTT cytotoxicity assay was employed to test effects of the essential oil on each human breast cancer cell lines. The GC-MS spectrums showed 9 major compounds, in which the highest chemical composition was related to thymol (42.16%), g-Terpinene (31.49%) and <em>p</em>-cymen (23.29%) compounds. <em>T. </em><em>copticum</em> essential oil showed good antitumor activity on SKOV3 and MDA-MB-231cell lines (<em>IC₅₀</em> of 208.13.6&micro;g/ml and <em>IC₅₀</em> 236.16&micro;g/ml, respectively). It also showed good activity against to tested bacteria. The MIC and MBC values of the bacterial strains sensitive to the essential oil were in the ranges of 0.4 to 3.1 mg/ml and 0.4 to 6.25 mg/ml, respectively. Because of the high concentration of phenolic compounds, the essential oil from <em>T. copticum</em> exhibited antimicrobial and antitumor activities, which deserve further research into the chemoprevention and treatment of human ovary and breast cancers as well as infectious diseases. &nbsp;</div> Antibacterial activities, Antitumor activity, Essential oil, Chemical compositions, Trachyspermum copticum 1 6 http://ijpt.iums.ac.ir/browse.php?a_code=A-10-117-1&slc_lang=en&sid=1 GHASEM MOHAMMADPOUR gha_mohammad@yahoo.com 10031947532846001570 10031947532846001570 Yes Department of Biology, Islamic Azad University, Sari Branch, Sari-Iran RAHMAT TAHMASBPOUR tahmasb63@gmail.com 10031947532846001571 10031947532846001571 No 2Department of Biology, Faculty of Basic Sciences, Hakim Sabzevary University, Sabzevar-Iran ALIREZA RAHMANI a_rahmani@gmail.com 10031947532846001572 10031947532846001572 No Marine Medicine Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran ALIAKBAR ALI ESFAHANI ak_esfahani@gmail.com 10031947532846001573 10031947532846001573 No Marine Medicine Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran