These studies were conducted to clarify the effects of sowing date on seed quality characters in soybean-sprouts. Six sprout-soybean cultivars were planted on three sowing dates in 2000 and 2001. Percentages of purple spot seed stain, seed coat-cracking and immatured seeds were higher in the May 25 sowing than later sowings. Pungsannamulkong showed the lowest percentages of seed coat-cracking and immatured seeds, while Hannamkong showed the highest percentages. The protein contents decreased as the sowing dates were delayed. Tawonkong and Pungsannamulkong showed the highest protein content on May 25 and June 15 sowings, and on July 5 sowing, respectively. The oil contents was not affected by the sowing dates, however, Somyeongkong and Tawonkong showed the highest and the lowest oil contents, respectively. The aglycone contents of isoflavone were the highest in the June 15 sowing followed by July 5 sowing and May 25 sowing in that order. Somyeongkong showed the highest contents of isoflavone and aglycone, while Tawonkong showed the lowest contents.