The purpose of this study was to assess the antibacterial activity of an ethanolic extract of Derris scandens against clinically isolated human pathogenic bacteria. Materials and methods: The ethanolic extract was assessed for antibacterial activity against ten human pathogenic bacteria at different concentrations (25 - 100 μg/ml) through the agar well diffusion method. Group 1 (25μg/ml), Group 2 (50μg/ml), Group 3 (75μg/ml) Group 4 (100μg/ml), Group 5 (positive control), and Group 6 (negative control) and calculated the zone of inhibition. Results and discussion: The ethanolic extract showed antibacterial activity against 8 clinical bacterial strains of the 10 pathogens tested. The highest concentration (100μg/ml) of the ethanolic extract showed a maximum of 20 and 22mm inhibition zone against E. coli and S. typhi. The mean values were 0.130, 0.141, 0.117, 0.194, and 0.120 The sample size was calculated with a pretest G power of 80%. The sample size per group is 6, and the total sample size is 60. Conclusion: The effective bacterial inhibition rate of Derris scandens might provide a promising beneficial agent against bacterial infection and help to develop future infectious disease drugs.