In glasshouse cultivation of eggplant (Solanum melongena L.), frequently in March-May, the distal ends of the young, fully developed leaves become yellow. Midribs, veins, and mesophyll show the symptoms, in contrast to the magnesium (Mg) deficiency known to occur in eggplant, i.e., interveinal chlorosis on the entire leaf. It was suggested that the symptoms were due to boron (B) deficiency although B supply was assumed to be sufficient. Then, the uptake could be restricted. To find out the real reason and if a fertilizer other than the normally used Borax could increase B uptake, an experiment was conducted in which 0, 5, 10, 20, and 200 mu M B as Borax and 20 mu M B as Solubor DF were compared. Leaftip yellowing occurred at all levels between 0-20 mu M B, especially at the zero level, but not at the 200 mu M B supply. Consequently, leaf tip yellowing can be considered as B deficiency. Borax and Solubor DF behaved the same. As long as leaf tip yellowing was moderate, it had no negative effect on production.