Boron (B) remobilization, mannitol and glucose concentrations, and the effect of B application on changes in soluble carbohydrates were investigated in various organs of bearing `Manzanillo' olive trees (Olea europaea L. `Manzanillo'). Following foliar 10B application to leaves of various ages, there was significant 10B export out of the treated leaves, and significant 10B enrichment in nontreated adjacent organs, including inflorescences and fruit. Results demonstrated that B can be remobilized from leaves of various ages, and that foliar-applied B is phloem mobile in olive. Soluble carbohydrate analysis determined that mannitol and glucose are the predominant sugars in all organs analyzed and that the mannitol concentration in the leaves is adequate to account for all B transport. This is consistent with observations in other species, where the presence of mannitol is known to facilitate phloem B transport through formation of a mannitol-B complex. Previous reports have indicated that B application can alter carbohydrate metabolism. In the present study, foliar B application significantly suppressed glucose concentration in the leaf petioles of all ages and increased mannitol in petioles of the current-year-developed leaves.