Some native rhizobia nodulating Acacia seyal, Acacia saligna, Dalbergia sisso, Macarium tipu, Leucaena leucocephala and Sesbania sesban were isolated from 10 different soil types along the Nile valley, North and South Sinai. While virgin soil samples of South Sinai showed no specific rhizobia nodulating D. sisso, M. tipu, L. leucocephala, and A. seyal, profuse nodulation was recorded with S. sesban and A. saligna in almost all soils. Nodule shape differed according to the host tree from globose to semi globose except L. leucocephala which formed elongated branched nodules. Slow-growing alkaline, producing rhizobia nodulating D. sisso, M. tipu and A. seyal formed small colonies of 1-2 mm diameter. On the other hand, rhizobia isolated from L. leucocephala, A. saligna and S. sesban were fast-growing acid producing candidates forming large-sized colonies of up to 4 mm in diameter. Rhizobia nodulating M. tipu as well as the reference strains R. leguminosarum bv. Viceae (441) and R. meliloti (ARC and A2) showed a minimum inhibitory Na-azide concentration of 15 µg/ml. In addition, MIC of around 35 µg/ml Na-azide was recorded for rhizobia nodulating S. sesban and A. saligna as well as the reference strains R. leguminosarum bv. Trifoli (TAL and ARC100) and bv. Phaseoli (1899 and ARC305). However, D. sisso and A. seyal rhizobia were highly sensitive to the presence of 5 µg/ml Na-azide in their growth medium. The legume tree rhizobia slightly varied in their resistance to four examined antibiotics and displayed scanty growth at 40°C. Salt (NaCl) concentration up to 4% in the growth medium of the isolates substantially retarded their growth and elongated their mean generation time. The examined tree legume rhizobia displayed high levels of host specificity where D. sisso and M. tipu profusely nodulated merely when inoculated with their specific rhizobial isolates.