Greenhouse and field experiments were conducted to evaluate the effectiveness of rhizobia isolates from two Rwandan soils and their effectiveness on two types of common bean under different agro ecological zones. A preliminary greenhouse experiment using Leonard Jars in Rubona Station was conducted to evaluate the potential of 174 rhizobia isolates. A selection criterion was based on nodule number, color, size and nodule weight. After 21 days, the best 50 isolates were selected for further evaluation in pots.