____________________________________________________________________________________________ *Corresponding author: Email: nkarimi@razi.ac.ir; nkarimie@yahoo.com; Annual Research & Review in Biology 4(16): 2646-2654, 2014 SCIENCEDOMAIN international www.sciencedomain.org Effect of Different Growth Regulators on Callus Induction and Plant Regeneration of Satureja species Naser Karimi 1* , Hamid Reza Ghasmpour 2 and Mozhgan Yari 1 1 Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran. 2 Department of Biotechnology and Chemical Engineering, Science and Research Branch, Islamic Azad University, Kermanshah, Iran. Authors’ contributions This work was carried out in collaboration between all authors. Author KN designed the study, performed the statistical analysis, wrote the protocol and wrote the first draft of the manuscript. Authors HRG and MY managed the analyses of the study. Author MY managed the literature searches. All authors read and approved the final manuscript.” Received 28 th November 2013 Accepted 14 th January 2014 Published 5 th May 2014 ABSTRACT Aims: This work was for the first time; undertaken to study the effect of different explant types and plant growth regulators on the callus induction and plant regeneration in both Satureja species. This protocol can be successfully employed for the large-scale multiplication and conservation of threatened this medicinal plant. Study Design: The development and maintenance of callus lines from the hypocotyl and leaves of Satureja hortensis and Satureja avromanica and the study of plant growth regulators on plant regeneration. Micropropagation of these aromatic plants can play a role in the protection of the natural ecosystem, guarantee a massive sustainable production and can provide standardized plant materials for diverse economical purposes. Place and Duration of Study: Experiments were carried out at the Department of Biology at Razi University of Kermanshah (Iran) in January 2011. Methodology: The sterilized seeds were cultured on Murashige and Skoog medium, and then the explants were cultured from seedling and transferred to a MS medium supplemented with different concentration of BAP, Kinetin, NAA and 2,4-D growth regulator hormones. Results: The highest percentage of callus formation frequency (96.67) in S. hortensis was Original Research Article