The research included determining the inhibitory effect of crude ethanol extracts of three herbaceous plants in some fungi and bacteria. The plants were Oxalis corniculata, Portulaca oleracea, and Euphorbia prostrata, while the fungi were Aspergillus niger, Alternaria sp., Fusarium sp. and Macrophomina phaseolina, the bacteria were E. coli, Klebsiella pneumoniae, Proteus sp., Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa. The inhibitory efficacy of three concentrations of each plant extract were 5, 10 and 20 (mg / ml) tested against the four fungi by measuring the diameters of the colonies in each concentration in addition to the control treatment, then the percentages of inhibition were calculated, and the effectiveness of the three concentrations against the six bacterial species were tested by measuring diameter of the zone of inhibition around disks saturated with concentrations of extracts as well as comparison with the diameters of inhibition obtained from standard antibiotic disks. It was noticed that the percentages of inhibition of fungi increased by increasing the concentrations of the extracts, so the concentration 5 mg/ ml had the least effect, while the concentration of 20 mg/ ml inhibited the growth of all fungi by 100% and for all three types of extracts. The results also showed that the fungus Alternaria sp. is more sensitive to plant extracts, followed by Fusarium sp., and the results also showed that the extracts of the O. corniculata and the P. oleracea had inhibitory activity against S. aureus, K. pneumoniae and E. coli, while the crude extract of the E. prostrata showed a great inhibition against all bacterial species and in direct proportion with the concentration..