Background & Aim:Vaginal disease has always been a great concern of women. Medicinal plants as natural resources with fewer side effects can effectively treat these infections given the diversity of these infections, resistance to antibiotics and side effects of existing drugs. The present study aimed to compare antimicrobial effects of methanol extract of Francoeuria Undulata on growth of several gram-positive and gram-negative bacteria causing vaginal infections.Experimental: Francoeuria Undulata as an indigenous Iranian plant was collected in two harvest times (T1 and T2). Methanol extract of aerial parts of the plant was prepared. The effects of various concentrations (62.5, 125, 250 and 500 mg/ml)of methanol extracts were studied onKlebsiella and Enterobacter as gram-negative pathogens. Minimum Inhibitory Concentration (MIC) of bacterial growth and MinimumBactericidal Concentration (MBC) were determined using macro-dilution method. Data analysis was performed using ANOVA.Results: The results showed that methanol extracts of aerial parts of Francoeuria Undulata inhibit bacterial growth of Klebsiella pneumoniae and Enterobacter aerogenes. MICs varied from 125mg/ml to 250 mg/ml in the old and new harvest times. Therefore, the smallest diameter of inhibition zone belonged to Klebsiella pneumoniae at 62.5mg/ml concentration in the old harvest time and the largestdiameter of inhibitory zone belonged tothe second strains of Klebsiellapneumoniae at 500mg/ml concentration in the new harvest time.Recommended applications/industries: The findings of the study indicated that methanol extracts of Francoeuria Undulata at two old and new harvest times had strong antibacterial and inhibitory effects on gram-negative bacteria causing vaginal infections. پرونده مقاله