Data presented in Table 1 revealed that number and mass of nodules of faba bean plants significantly decreased as soil alkalinity in creased. An increase from pH 7.5 to 9 resulted in only 50%nodulation. It is very interesting to note that the dual inoculation of R. leguminosarum bv. viciae STDF-Egypt 19 (HM587713) and mix-ture of mycorrhizal fungi significantly (p < 0.05) increased numberof nodules by 4.02 times more than the control plants grown at pH level of 8.5, while inoculation of plants with R. leguminosarum bv.viciae STDF-Egypt 19 (HM587713) alone increased the number of nodules 3.79 folds more than that of uninoculated plants grown at the pH level of 8.5. Moreover, dual inoculation increased the number of nodules by 1.34 times more than plant inoculated with R.leguminosarum bv. viciae STDF-Egypt 19 (HM587713) alone. Total nodule weight per plant followed a similar pattern to number of nodules. The inhibitory effect of alkalinity stress on nodulation of Vicia faba appeared at the pH level of 8 and became more in hibitory with increase in alkalinity level