We investigated the reproductive capacity of starry flounder Platichthys stellatus from the Uljin (UJ) marine ranching area and compared it to that of P. stellatus from the coastal waters of Pohang (PH). In UJ, female gonadosomatic index (GSI) peaked in October ($3.14{pm}0.87$) and male GSI was high in October and December. In PH, female GSI peaked in January ($18.64{pm}2.15$) while male GSI began to increase in October and remained high until March. Most ovaries of UJ females were immature with perinucleus oocytes, although the testes of UJ males were ripe in January. Both the ovaries and testes of PH starry flounders were ripe from January to March. The plasma estradiol-$17{eta}$ ($E_2$) levels of UJ females were highest in October ($4.09{pm}1.90$ ng/mL) although the testosterone (T) levels of UJ males were highest in December ($3.81{pm}0.78$ ng/mL) and decreased gradually until April. The $17{alpha}$,$20{eta}$-dihydroxy-4-pregnen-3-one ($17{alpha}20{eta}P$) levels of UJ females were not detected. The E2 levels of PH females were highest in December ($36.25{pm}33.07$ ng/mL) and $17{alpha}20{eta}P$ levels were highest in March ($5.51{pm}0.95$5 ng/mL). The T levels of PH males were highest in December ($4.03{pm}1.34$ ng/mL) and decreased gradually until October. Taken together, these results suggest that most females from UJ did not reach maturation with a spawning period that was considered to be between December and January.