Unfavorable environmental conditions and inappropriate culture practices have increased the vulnerability of cultured fish to disease infection. Up to date many studies have aimed to determine a feeding regimen to maximize productivity; however， very little information on immune responses of cultured fish in response to underfeeding or overfeeding is available. Therefore， a preliminary study was conducted to evaluate effects of graded feeding levels (i.e.， food availability) on growth performance and immune-related gene expression of juvenile olive flounder (Paralichthys olivaceus). Six different feeding rates including 1， 4， 7， 10， 13， and 16% body weight per day (BW/d) were randomly assigned to three replicate tanks stocking 150 fish (average initial body weight: 0.27?±?0.02?g; mean?±?SD) per tank. A feeding trial lasted for two weeks. Based on the results of the weight gain， nutrient gain， and whole-body compositions and energy content， the feeding rate of 10%， 13%， and 16% BW/d resulted in high nutritional status， whereas the feeding rate of 1% and 4% BW/d resulted in low nutritional status. Intermediate nutritional status was observed at the feeding rate of 7% BW/d. In the given rearing conditions the optimum feeding rate resulting in the maximum growth was estimated to be 11.9% BW/d based on the quadratic broken-line regression model， chosen as the best-fit model among the tested models. Expression of immune-related genes including IL-8 and IgM was significantly down-regulated in the flounder fed at 1% BW/d in comparison to those fed at 7% BW/d. Interestingly， expression of these genes in the flounder fed at 10%， 13%， and 16% BW/d was relatively down-regulated in comparison to that of the flounder fed at 7% BW/d. Although no statistical difference was detected， overall response patterns of other immune-related genes， including TLR3， polymeric Ig receptor， lysozyme C-type， GPx， SOD， and Trx followed what IL-8 and IgM exhibited in response to the various feeding rates. Given the current challenges in aquaculture of the flounder our findings suggest to prohibit underfeeding or overfeeding (i.e.， ad-libitum feeding) when culturing the young flounder.