This research was carried out to determine the 25-Hydroxyvitamin

[25(OH)

] 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/

(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)

fraction was separated by Sep-Pak silica cartridge. The 25(OH)

concentration was measured by normal phase HPLC. The negative control chicks Presented 25(OH)D

17.5 ng/g liver. When 0.204mJ/

was treated to whole body of chicks, the 25(OH)

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/

was applied, the 25(OH)

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)

were 23 and 43.9 ng/g as chicks were exposed to UVB light with dose of 0.204 and 0.408mJ/

, 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)

at 42 hr after exposure, and the peak value was presented earlier by 24 hr than that in the low dose treatment.