Screening of some native Rhizobium isolates obtained from root nodules of blackgram, greengram and pigeonpea of six districts viz., Kamrup, Nalbari, Nagaon, Sonitpur, Lakhimpur and Jorhat of Assam were done. Out of the total 54 pure culture isolates, only 14 were found to be nodulation positive of which 9 isolates could nodulate blackgram and greengram. When subjected to antibiotic sensitivity test, these 9 isolates showed varying antibiotic resistance pattern and isolate AR1 was the most resistant against 9 antibiotics. Rhizobium isolate AR1 was found to be most effective in respect of number of nodules (75 and 100), nodule dry weight (0.41 and 0.38 g), shoot dry weight (6.8 and 7.2 g), root dry weight (2.8 and 3.1 g) and percentage of nitrogen content (3.25% and 3.40%) both in blackgram and greengram, respectively. Performance of greengram with all the isolates was better in respect of above parameters than blackgram. Rhizobium isolate AR1 also showed the highest nitrogenase activity in the root nodules of blackgram and greengram (4.02 and 4.25 mole/g/h).