Paraserianthes falcataria is naturally had symbiosis with nitrogen-fixing bacteria (Rhizobium). Urea is fertilizer with high content of nitrogen (46%). The research aimed to study the effect of Rhizobium inoculation on P. falcataria seedling growth; the influence of various concentrations of urea on P. falcataria seedling growth and the interaction of Rhizobium and urea at Rhizobium colonization and seedling growth. The research design was factorial completely randomized design, consisting of two factors, the first factor was the Rhizobium inoculation and the second factor was the doses of urea wich were 0, 2, 4 and 8 grams. The results showed that Rhizobium inoculation could increase the high, diameter, formation of effective nodule, and dry weight of P. falcataria seedling; added 4 grams urea produced the best growth; while Rhizobium inoculation without fertilization produced the highest Rhizobium colonization and the best growth.