We investigated the characteristics and rate of development of allotriploid embryos derived from a cross between female olive flounder Paralichthys olivaceus and male starry flounder Platichthys stellatus. The allotriploidy was induced by cold shocking fertilized eggs three minutes post-fertilization at 3°C for 45 minutes. The average cellular DNA content of the allotriploid embryos was 2.06±0.03 pg/cell, which is equal to the sum of the cellular DNA content of a diploid olive flounder (1.42 pg/cell) and a haploid starry flounder (0.66 pg/haploid cell). The first cleavage, mid-blastula, gastrula and Kupffer`s vesicle appearance stages of the allotriploid eggs began at 1.5, 8, 13 and 26 hours after cold shocking at 18°C, respectively. The developmental rate of allotriploid eggs was equivalent to that of diploid and triploid olive flounder eggs at 10, 14 and 18°C. However, the hatching times of allotriploid eggs, 7 h at 10°C, 5 h at 14°C and 4 h at 18°C, were earlier than those of diploid and triploid olive flounder.