Staphylococcus aureus and Escherichia coli are the most common pathogenic bacteria that causes extreme threat. Antibiotic resistance of these two bacteria are now currently increasing and developing into a multidrug-resistant bacterium. Nonetheless, the continuous analysis on the synergistic effects of antibiotics and medicinal plants are now trending, but still may leave side effects to human. Hence, this study aims to analyze the synergistic effect of the two known antibacterial plant extracts. Using experimental research design, the researchers used Citrus microcarpa (calamansi) and Vitis vinifera (grapes) against Escherichia coli and Staphylococcus aureus. The extracts were divided into different concentrations to wit: 100%, 75%, 50% and 25%. The result shows that the higher the concentration, the more effective antibacterial agent is the combined extract. Using FIC, the researchers found out that the combination of Citrus microcarpa and Vitis vinifera against both bacteria is indifference. Hence, the combined extract can be used as antibacterial against the two bacteria but does not become synergistic.