Potato tubers treated at 4℃. for 4 weeks were irradiated with a dose of 0.12 kGy from ^(60)Co source and stored at 20℃, 70∼90 humidity for 5 weeks. Changes of α-amylase, peroxidase, indole acetic acid oxidase, indole acetic acid synthesizing enzyme activities were determined. In addition, treatment of gibberellin or indole acetic acid to tubers irradiated were carried out to examine reversal of sprout-inhibition of tubers irradiated. Results are as follows; 1. Irradiation by γ-ray at 0.12 kGy dose inactivated easily the enzyme activities in vitro. D_(37) values obtained were 0.94, 0.36 kGy for α-amylase and peroxidase, respectively. 2. Complete inhibition of the tuber sprouting was resulted by the irradiation of tubers with a dose of 0.12 kGy. 3. The indole acetic acid oxidase activity increased 2 times immediately after irradiation. Meanwhile, indole acetic acid synthesizing activity decreased about 50∼75% for 5-week storage in irradiated potatoes, whereas the activity increased about 3.5 times along with sprouting; in non-irradiated tubers. 4. In morphological aspects, deformed buds with necrosis in the meristmatic tissue were developed in irradiated tubers. Treatment of gibberellin or indole acetic acid at the concentration. of 100 or 20 ppm to the irradiated tubers reversed the sprout-inhibition partially. Nevertheless, the deformed buds remained with out change.