In this study, 4 different extracts of Thymus praecox subsp. grossheimii var. grossheimii (Ronniger) an endemic species of genus Thymus were investigated on gram positive and gram negative test bacteria for the antibacterial activity. The plant extracts were obtained via Soxhlet method, and the antibacterial activities were determined by macrodilution liquid (tube) method (MIC). Results indicated that 4 different extracts at different concentrations showed antibacterial activities on both gram positive and gram negative strains. The highest antibacterial activity was observed in acetone extract against Bacillus cereus, whereas the lowest activity was seen in methanol extract against Klebsiella pneumonia, Proteus mirabilis, Pseudomonas aeruginosa and Salmonella Enteritidis. In conclusion, it was determined that Thymus praecox subsp. grossheimii var grossheimii (Ronniger) has an antibacterial activity against gram positive and gram negative test bacteria.