This research was carried out to determine the 25-Hydroxyvitamin $D_3$[25(OH)$D_3$] content in liver of broiler Hubbard chicks fed vitamin VD-deficient diet for 31 days in a subdued light room and exposed to UVB light (maximum intensity at 297nm) with dose of 0.204 or 0.408 mJ/$ extrm{cm}^2$(30 or 60 min irradiation) . The lipid in liver collected at 0~138 hr after irradiation was extracted by chloroform-methanol(2：1, v /v) and 25(OH)$D_3$ fraction was separated by Sep-Pak silica cartridge. The 25(OH)$D_3$ concentration was measured by normal phase HPLC. The negative control chicks Presented 25(OH)D$_3$17.5 ng/g liver. When 0.204mJ/$ extrm{cm}^2$ was treated to whole body of chicks, the 25(OH)$D_3$ level was increased to 37.8 ng/g at 12 hr after irradiation, the peak concentration, 40.5 ng /g was appeared at the time of 86 hr, and decreasing trend was shown thereafter until 138 hr, the final time in this study. When 0.408 mJ/$ extrm{cm}^2$ was applied, the 25(OH)$D_3$ content was 36.7 ng /g liver at 12 hr, 61.4 ng/g(maximum value ) was appeared at 42 hr, and 39.5 ng /g at 138 hr. The increased absolute amounts in liver 25(OH)$D_3$ were 23 and 43.9 ng/g as chicks were exposed to UVB light with dose of 0.204 and 0.408mJ/$ extrm{cm}^2$, respectively. Consequently, it was found that when double dose of UVB light was irradiated to the chicks, their liver samples produced nearly double 25(OH)$D_3$ at 42 hr after exposure, and the peak value was presented earlier by 24 hr than that in the low dose treatment.