Abstract: Background and Objective: The using the active antibiotic option that treats the infectious pathogenic bacteria in humans due to antibiotic-resistant strains is limited. The finding of the new antibiotic reagent source is required. This research aimed to investigate in vitro anti-human pathogenic bacterial activity of Cissus quadrangularis against seven human pathogenic bacteria isolated from clinical specimens of patients at Roi Et hospital. Materials and Methods: The C. quadrangularis were extracted with extraction solvents. The plant extracts were tested on seven human pathogenic bacteria using an agar disc diffusion assay. The broth microdilution assay and colorimetric assay were used to determine the Minimal Inhibition Concentration (MIC) and Minimal Bactericidal Concentration (MBC) values of C. quadrangularis extracts. Results: The inhibition zone was measured in mm. The C. quadrangularis extracted with ethanol was presented the largest inhibition zone at 15 mm against Enterococcus faecalis and Pseudomonas aeruginosa (CoR-PA). The result of the lowest MIC value was at 0.19 mg mL–1 was presented in ethanol extraction against A. baumannii. The lowest MBC values were at 3.13 mg mL–1 were obtained from methanolic and ethanolic extracts against S. maltophilia and E. faecalis. Conclusion: This is the first report to present the novel information of antibacterial profile of C. quadrangularis extracts against human pathogenic bacteria isolated from clinical specimens of patients at Roi Et hospital which can be developed further as a natural antibiotic drug for treating bacterial infectious diseases.