Abstract: The toxic effect of different concentrations of some heavy metals (Cadmium, Zinc and Lead) on the growth of cultured Rhizobium leguminsarum biovar vicia was studied and their LD50 toxicity were determined. The 50% inhibition of bacterial growth was achieved by contaminating the culture with 2.1 μM of Cadmium, 30 μM of Zinc or 290 μM of Lead. In attempts to counteract the toxic effect of these heavy metals, several compounds were tested to reactivate the Rhizobium growth and to abolish the toxic effect, either partially or totally, which is caused by the presence of heavy metals (as in case of presence of sewage sludge). Positive results were obtained from the addition of some of these compounds as: Mannitol and Glutamate, 5,7 dihydroxyflavone, Thiamine hydrochloride, Calcium chloride and Calcium ionophore A23187. Their most effective concentrations were determined for each compound in the presence of each heavy metal at its concentration of LD50. An average recovery in bacterial growth, in presence of each of Cadmium, Zinc and Lead, individually, were as fellows: 97, 90, 88, 84 and 83%, due to the individual addition of 214 mM mannitol + 42 mM glutamate, 0.96 mM thiamine hydrochloride, 7.79 mM calcium chloride, 2.98 x 10-3 mM calcium ionophore A23187 and 0.69 mM of 5,7-dihydroxy flavone, resepectively.