From immature young fruits of Ziziphus mauritiana and Aegle marmelos gibberellin-like factors were isolated. The factors a1, a2, a3, and a4 of Ziziphus were similar to gibberellins A1, A3, A9, and A4. The factors x1, x2, x3 isolated from Aegle marmelos behaved similarly to gibberellins A1, A3, and A9on paper, thin layer, and silicic acid, celite column chromatographic techniques. In both fruits peak gibberellin activity occurred during the early period of fruit growth and decreased during rapid fruit growth. The possible significance of the finding is discussed in view of fruit development. © 1985, Gustav Fischer Verlag, Stuttgart. All rights reserved.