In order to evaluate the effect of different bacterial strains on common bean yield and it`s components and to estimate the best bacteria and cultivar`s combination, field experiment was carried out at Shahrekord in Iran (latitude 32°44 / N, 2100 m asl) during May - October 2002 on a sandy -loam soil. The experiment was a spilt plot in randomized complete block design with four bacterial strains L-78, L-47, L-125, L-109 and non-inoculated controls including application of nitrogen fertilizer treatment (100 kg N ha-1) and without application of nitrogen fertilizer (-N) as the main plots. Three cultivars included Shahrekord local (Cranberry bean), Talash (Cranberry bean) and Shahrekord local (Red Mexican type) were assigned as the subplots. The results revealed that high significant difference (p<0.01) in seed yield, seed and pod number per plant, LAI at 40-50% flowering (50 days after emergence), harvest index (HI) and dry matter yield among seed inoculated with different strains and non-inoculated controls (+N and -N treatment). Seeds inoculated with L-125 showed higher seed yield than other strains, but similar was observed in seed inoculated with L-109, L-78 strains and non-inoculated control (+N).