Objective To investigate solar radiation and its effects on human tooth enamel electron spin resonance (ESR) dosimetry. Methods 11 tooth enamel samples were prepared by mechanical method. The intensity of solar iUuminanee was measured with a light meter, the measured illuminance was converted to insolation using a coefficient. Summation of solar radiation was evaluated. Enamel samples were exposed to 60 Co γ rays followed by sunlight on sunny days, and ESR spectra were scanned after different exposure. Results The solar radiation to the samples was (580 ± 16) MJ/m2. Solar exposure also caused dosimetrie signal. The perpendicular component of dosimetrie signal increased linearly with the amount of solar radiation, another signal close to background tended to saturation. Conclusions The average effect of the solar radiation on the signal was be used to recognize the effect of solar radiation on the enamel, and estimate external dose accurately.