The methanol extract of Piper ribesoides Wall, was evaluated for potential antimicrobial activity against Staphylococcus aureus (Rosenbach). The methanol extract of P. ribesoides root was effective on S. aureus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of the methanol extract of P. ribesoides were 3.125 mg/ml and 6.250 mg/ml, respectively. Apart from the antibacterial effects, imaging using scanning electron microscopy (SEM) was done to determine the major alterations in the microstructure of the S. aureus. The main abnormalities noted via SEM studies were alterations in morphology and complete collapse of the bacterial cells after 36 h of exposure to the extract. The effect of the extract on the growth profile of the bacteria was also examined. The extract changed the normal growth profile of S. aureus, thus confirming the bactericidal effect of the extract on S. aureus