Yield responses of bean are often limited by the nitrogen deficiency, being the most common limiting factor for the growth of the plants. Common bean (Phaseolus vulgaris L.) is often considered as a poor N2-fixing legume. Thus, it is often cultivated with a complement of mineral nitrogenous fertilization to correct this deficiency and to raise the yields. The symbiotic nitrogen fixation (SNF) provides an ecologically acceptable alternative to the high applications of nitrogenous fertilizers, especially in Europe, and an economic alternative to the limited access to these fertilizers in the developing countries. The objectives of the work are i) to study the genotypic diversity represented by local populations of bean, ii) to identify those populations which can be useful to improve SNF potential as well as iii) to determine the degree of genetic diversity of the native populations of rhizobia that nodulate P. vulgaris in the soils of Galicia and their potential to fix N2 with local populations of bean.Research was supported by the projects INTRAMURAL CSIC 200110E016 and PHASEORHIZ FP6-510564 from the EU. The authors thank the Xunta de Galicia for funding.Peer reviewed