Abstract: The effects of gibberellic acid on the changes of growth substances and some carbohydrates in pea seedlings were investigated. The principal results obtained are as follows: (1) When the peas were imbibed with an aqueous solution of gibberellic acid for six hours, the first internode showed the most pronounced growth response as compared with the other parts of the pea seedlings. (2) The growth substances in the terminal bud of the control and that of the gibberellic acid treated seedlings were different from each other qualitatively and quantitatively as demonstrated by means of the wheat straight growth and rice seedling test on paper chromatograms from purified extracts, In the control plants considerable amounts of inhibitor β complex was present whereas in the treated seedlings little or no such inhibitor was detected. The contents of indole acetic acid and indole acetonitrile of the control plants were higher than those of the treated plants. In addition, trace amount of gibberellic acid was found in the treated plants and none was detected from the controls. (3) The amounts of reducing sugars and cell wall substances of the first internode of treated seedlings were 140%–143% and 150%–174%, respectively, as compared with those of the control plants. Also the oxygen uptake of the first internode of the treated plants was 1.5–2 times of that of the corresponding part of the controls. (4) Analysis of the contents of starch and reducing sugars in the cotyledons revealed that the former decreased while the latter increased as compared with the controls. The activity of the amylases of the treated seedlings was also higher. It appears that imbibing peas with gibberellic acid enhanced the growth of young pea seedlings (especially the first internode). There were an increase in respiration, an increase in reducing sugar and cell wall material in this internode, and an increase in amylases activity and starch disappearance in the cotyledons. All these effects may have causal relation with each other and with the decreasing of a natural growth inhibitor in the terminal bud.