Present work was conducted to investigate the combined effects of gamma-radiation and chemical treatment on the inhibition of sprouting and decay of potato tubers. Irish Cobbler, Apollo and Shimabara potato tubers were immersed in 1000, 2000 and 3000 ppm solution of salicylic acid for 2 minutes, and then irradiated at doses of 5, 10, and 15 krad using an indoor gamma room of approximately 10,000 Ci of $^{60}Co$. Treated tubers were stored for 8 months at room temperature. The results of this work are summarized as follows: 1. Moisture content of irradiated potato tubers was changed less than the control, and decreased gradually along with an extended storage period. Ascorbic acid content was remarkably decreased by gamma-radiation and an extended storage period. 2. Reducing sugar content of irradiated potato tubers tended to increase greatly compared with unirradiated potato tubers, however, starch content of irradiated potato tubers decreased compared with the control. Reducing sugar and starch content of all groups also decreased gradually along with an extended storage period. 3. The storageability of Irish Cobbler variety was best among three varieties and Shimabara variety was worst among them when gamma-radiation is treated singly or in combination with the chemical. Sprouting of potato tubers was more suppressed in combination treatment than single treatment. 4. Decay of potato tubers was more reduced in combination treatment than single treatment. Chemical treatment or gamma-radiation followed by chemical treatment had no influence on decay or spronting of potato tubers. 5. Weight loss of potato tubers was considerably increased as storage period became extended. Shrinkage was, more serious in Shimabara than in rish Cobbler.