Microcapillary tubes were inserted directly into xylem vessels of leaves and stalks of sugar cane (Saccharum spp.) to determine the form in which nitrogen is translocated from the roots towards the leaves. On a low nitrogen regime, the xylem fluid of both sugar cane and related species and genera contained nitrogen dominantly in the amino form. Nitrate was also present and increased markedly in some varieties when the supply of nitrate fertilizer to the roots was increased. The amino N and nitrate N levels tended to be lowest in the xylem fluid of those leaves most active in photosynthesis.