Summary Peppermint ( Mentha piperita L.) is time-honored for its medicinal properties and its antimicrobial characteristics are well established and supported in the literature. In the present study the composition and in vitro antimicrobial activity of Mentha piperita essential oil ( MpEO ) alone and in combination with silver ions (Ag + ) against the cultures of Escherichia coli , Staphylococcus aureus and Candida albicans is highlighted. The nature of the interaction was studied from fractional inhibitory concentration indices (FICIs) for MpEO plus Ag + , calculated from checkerboard microdilution assays. On gas chromatography–mass spectrophotometry (GC–MS) analysis, MpEO showed a high content of menthol (34.82%). FICI values depicted a high synergism of MpEO with Ag + against C. albicans (∑FIC = 0.48) and E. coli (0.40), while as indifferent effect against S. aureus (0.95). No antagonistic activity was seen in the strains tested in the present study. Combinational activity was further confirmed by disk diffusion and time kill curve assays. From these results we suggest that MpEO with Ag + have great potential as antimicrobial agents required to achieve an effective reduction in opportunistic pathogenic microorganisms.