Abstract: The field experiments were conducted during 2000 at Tandojam, Pakistan to evaluate the effect of Rhizobium japonicum inoculum doses of liquid culture on the growth and seed yield of soybean crop. One liter liquid culture medium was prepared by standard procedure by adding 0.5g K2HPO4, 0.2g MgSO4, 0.1g NaCl, 0.05g yeast extract, 10.0g Minitol, and 1000ml distilled water. Six Rhizobium japonicum doses (10, 15, 20, 25, 30 ml, and untreated control were laid-down in Randomized Complete Block Design. The adequate level of 25 ml with 300 grams sand maize as seed treatment inoculant was found more effective for maximum growth and seed yield as compared to higher and lower doses of Rhizobium japonicum. Thus, it was concluded that Rhizobium japonicum exhibited the positive change in terms of enhanced growth and seed yield. The satisfactory results would be achieved if, the soybean seed will be treated with 25 ml of Rhizobium japonicum inoculum.