Nitrogen is one of the most abundant elements, and BNF is the main source of nitrogen forrnLegumes plants. Field Pea is one of the most important Legumes plants and widely grown inrnTigray regional state. Although some studies have covered some areas of Tigray in relation tornbiological nitrogen fixation, there was no comprehensive study on the crop in the mostrnimportant pulse growing regions of Southern Tigray. The present study, therefore, wasrndesigned with the objective of isolating and characterizing root nodule bacteria from threernWoredas of southern Tigray, and evaluating their symbiotic effectiveness on field pea. Thernresult will serve as base line data for future endeavor of utilizing biological nitrogen fixingrnsystem of field pea to increase productivity into low-input agriculture of the region and therncountry at large. Thirty three soil samples were collected from field pea (Pisum sativum)rngrowing areas of Southern Tigray (Ofla,Endamokoni and North western parts of AlamatarnWoreda) . The soil samples were brought to Applied Microbiology Laboratory for furtherrnprocessing. For induction process the soil samples mixed with the extensively washed andrnsterilized river sand and filled in to surface sterilized 3kg capacity plastic pots. Seed of therncultivar Pisum sativum Addi surface sterilized and sown into each pot and placed in therngreenhouse condition .After 55 days plants were uprooted and collected nodules of all isolatesrnwere induced into the original host plants. All isolates characterized their morphological andrnphysiological characteristics. All isolates formed watery and mucoid colonies on YEMArnmedium, their mean growth time mostly between 2 &4 hours and failed to grow on peptonernglucose agar medium and to solubilize inorganic phosphate. Almost all isolates were tolerate tornpH 5to 9, salt concentration, and at temperature of 15oc to 35oc. The isolates were also tolerantrnto ampicillin, penicillin, erythromycin and chloramphenicol, but sensitive to gentamycin andrntetracycline. All isolates utilized to sucrose, glucose and D-manitol but few isolates utilizedrncitrate, cellulose and starch, and the isolates utilized many amino acids as the source ofrnnitrogen. The numerical analysis based on the 54 phenotypic characteristics of isolates wasrnclustered into six groups. The mean nodule number, nodule dry weight and mean shoot dryrnweight of the host plants inoculated with different isolates showed variations. After in fieldrnexperiments, the isolates (AAUFPR05, 06, 07,11,16,18 and 30, 37, 39 and 43), and particularlyrnAAUFPR 07and 28 can be recommended as inoculants in the future. The above isolatesrnshowed good physiological,eco-physiological and symbiotic characteristics.rnKey Words: Field pea, Tigray, phenotypic characters, symbiotic effectiveness, Rhizobium