The effectiveness of the symbiotic association of rhizobia with peanuts grown in four production areas of Texas was investigated. This study was undertaken because farmers indicated that they were obtaining yield increases from fertilizing peanuts with N. The location and abundance of nodules on peanut roots indicated that numbers of rhizobia in 16 of 17 fields sampled were adequate for good to fair nodulation. However, nodules sampled from only one of the four production areas consistently contained leghaemoglobin. Twenty-one strains of rhizobia were isolated from peanut nodules from the four areas. Greenhouse trials revealed that only a few strains were highly effective. Results of these studies suggest that peanuts grown in Texas would respond to inoculation with highly effective rhizobia. Field tests are needed to verify the potential benefit from inoculation.