A study was carried out to establish the detection method of irradiated corn, potato, and sweet potato starches. The samples were packed in polyethylene bags and irradiated with 1, 3, 5, 7, 10, and 15 kGy using a Co-60 irradiator. The maximum viscosity of irradiated and unirradiated corn, potato, and sweet potato starches reduced by increase of irradiation dose levels and showed significant differences which clearly showed the effect of irradia-tion dose levels (p<0.05). Regression expressions and coefficients (p<0.000) or corn, potato, and sweet potato starches were y=-38.538x+718.23(r2=0.9761), y=669.97e-0.1372x (r2=0.9820) and y=-42.544x+730.26(r2=0.9939), respectively. Nor-malized parameter A,B and C values showed a dose dependent relationship and were a better parameter for detecting the irradiated starches than that of the maximum viscosity itself.