Reclaimed tidal areas for rice cultivation are irrigated with salt mixed water when there is severe drought. Therefore, we identified the critical concentration of saline water for rice growth on a reclaimed saline soil in Korea. The experiment was conducted at the Kyehwado substation of the National Honam Agricultural Experiment Station (NHAES) during 2001-2002. Two experimental filed with 0.1-0.2% for low soil salinity levels were used. The experiment involved four levels of salt solution mixed with sea water (at 0.1, 0.3, 0.5, 0.7%) compared with a control using tap water in split-plot design with three replicates. Saline solution was applied only two times at seedling stage (10 DAT and 25 DAT) for 5 days. Gyehwabyeo and dongjinbyeo, japonica rice varieties, were used in this experiment. Plant height and number of tillers sharply decreased in the 0.5% saline water in low soil salinity level and 0.1% in medium soil salinity level. For yield components, panicle number per unit area and percentage of ripened grain dramatically decreased in the 0.5% saline water in low soil salinity san 0.1% in medium soil salinity level. But 1,000-grain weight of brown rice decreased sharpy in the 0.5% saline water in low soil salinity and 0,3% in medium soil salinity, indicating that this components. Milled rice yield decreased significantly with saline water level in booth low and medium soil salinity. In the 0.7% low saline soil, the yield index was only 36% compared with the control. In medium soil, even the control plot showed only 62% yield index compared with the control in the low soil salinity treatment. Results indicated that the critical concentration of rice production was 0.5% in low soil salinity and tap water in medium soil salinity.