The following experiment investigated the effect of meropenem antibiotic on the activity of glutathione-S-transferase (GST) isoenzymes. This effect was estimated spectrophotometrically at different concentrations of meropenem using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate. The obtained results revealed that meropenem antibiotic demonstrated an inhibitory effect on GST activity at low tested concentrations (0.25, 0.5, 1 and 2.5 mM) that resulted in 30.5, 39.4, 45.1, and 100% inhibition, respectively. Also, results provided that the meropenem concentration required to reduce the GST activity to half equal to 1.266 mM. After applying the Line weaver-Burk blot and equation, it was noted that both Km and Vmax values decreased in the presence of meropenem, indicating uncompetitive inhibition. In conclusion, meropenem antibiotic is a potential inhibitor for GST. Therefore, it will be crucial to consider the metabolic defense systems when selecting the dosages of this antibiotic to be utilized for the treatment of infections.