The nodulation ability was determined of native Frankia strains (ChI1, ReI4, ReI6, TtI42, and TqI15) isolated from rhamnaceous species indigenous to Chile. All strains tested nodulated other Rhamnaceae host species within one or more genera, i.e., TtI42 nodulated seedlings of Trevoa trinervis, Retanilla ephedra, and Talguenea quinquenervia. Trees from other families such as Casuarina (Casuarinaceae) were not nodulated by the Frankia strains mentioned above. These results suggest that the five strains isolated from rhamnales could belong to the same cross inoculation group because they exhibited the same level of promiscuity. The effectivity of Frankia for nitrogen fixation was established by measurement of acetylene reduction activity in planta. Two strains (ReI6 and TtI42) were found more effective than the others and improved the total dry weight and shoot height of Retanilla ephedra seedlings. These studies may facilitate the choice of selected rhamnaceous Frankia pairs for arid soil afforestation, since these plants are naturally adapted to this environment in Chile.