Essential oils are complex mixtures of volatile aromatic compounds derived from the secondary metabolism of plants, and which have several chemical components responsible for their therapeutic and organoleptic properties, among them, the class of terpenes, specifically alpha-pinene, a compound organic, which acts as an antibacterial agent. Among the multiresistant strains, the gram-negative species Proteus mirabilis is responsible for causing urinary tract infections. Thus, the present study aims to evaluate the antibacterial potential of (+) - alpha-pinene against the ATTC (American Type Culture Collection) standard strain of Proteus mirabilis ATCC 25933. Knowing the sensitivity of the bacterial strain, after the test of microdilution in broth, we intend to evaluate the antibacterial potential, ie the time by which the compound was able to act to eliminate the bacterial strain. For this, the present work used the methodology of Time Killing (Bacterial). In this sense, the strain was initially peeled into Mueller Hinton Agar (AMH) 24 hours prior to the test. For the analysis of the death curve in the time intervals 0, 2, 4, 8 and 24 hours of the MIC and MICx2 of the α-pinene, MIC of the amikacin and negative control, that is, the culture medium plus the bacterial inoculum. A 10 μL aliquot of the well contents and diluted in a 0.9% physiological solution was withdrawn, thereby forming a suspension, and an aliquot of 10 μL of this new dilution was then withdrawn and plated on plates containing Mueller Hinton agar with the aid of a Drigalski handle. This procedure was repeated at times t0, t2, t4, t8 and t24. The plates were then incubated at 35 ± 2 ° C for 24 hours and the number of colony forming units (CFU) counted, adjusting with the dilution factor used in each procedure. It is worth noting that this work is a pioneer in the evaluation of the antibacterial activity of the positive enantiomer of α-pinene, considering that there are no reports in the literature of studies against this bacterial. The MIC of amikacin was shown to be able to totally inhibit the growth of the strain within the first two hours, and the alpha-pinene MIC inhibited the growth of P. mirabilis after 24 hours. Inhibition occurred progressively at times 2, 4 and 8 hours until its total inhibition at 24 hours. However, the MICx2 of the alpha-pinene was also able to inhibit the total growth of the strain, but in a less time, requiring 8 hours for its total effect. It is therefore observed that the test substance, (+) - alpha-pinene has therapeutic potential to treat infections resulting from this bacterial strain. It is hoped that this study may support the development of future research to better elucidate the mechanism of action, the clinical safety of the substance as well as the toxicity of the compound. Thus, it may be a naturally occurring compound used as a new therapeutic option in opportunistic infections caused by Proteus mirabilis.