This experiment was conducted to study the varietal and ecological difference of rice in heading date by night illumination. The degree of delay in heading date and days from heading initiation to full heading DHIF) of rice were in the order of mid-late maturing cul tivars (MLC) > medium maturing cultivars (MEC) > early maturing cultivars (EAC) > very early maturing cultivars (VEC). However, the MEC showed significant variation in days to heading; Kwanganbyeo delayed significantly, but Ansanbyeo did not. The comparative sensitivity of differ ent rice ecotypes per lux in delayed heading was 0.09~0.10, 0.14~0.26, 0.19~O.58, and 0.35-0.54 days in VEC, EAC, MEC, and MLC, respectively; the shortest in Odaebyeo (0.09 day), moderate in Daeanbyeo (0.35 day), and the longest in Kwanganbyeo (0.58 day). Difference of DHIF was 0~1 day in VEC, -1~2 days in EAC, O~l6 days in MEC and 6~18 days in MLC under 50~70 lux compared to 2 lux; Daejinbyeo (-1 day), Hwaseongbyeo (6 days), Chucheongbyeo (9 days), Kwanganbyeo (16 days), and llpumbyeo (18 days).