The effects of four different rearing temperatures (15, 18, 21, and 24 degrees C) on reversed asymmetry and larval development in the hatchery-reared larvae of the flounder, Platichthys flesus luscus, were investigated in this study. Incidence of reversed asymmetry (sinistral forms) were found to be 13.0, 10.4, 11.6 and 21.3% at 15, 18, 21 and 24 degrees C, respectively. The sinitrality rate was not affected by temperature between 15 degrees C and 21 degrees C, while this incidence was significantly higher at 24 degrees C (P<0.05). At completion of the metamorphosis (day 60), juvenile final total length and survival rates were 18.4, 19.9, 18.8, 15.7 mm and 13.5, 9.0, 10.6, 9.2% at 15, 18, 21 and 24 degrees C, respectively. The results of the present study strongly suggest that rearing temperature not only influences growth and survival during the larval development but also reversed asymmetry in the flounder at the metamorphosis, especially at high temperatures.