In this study, the effects of hazelnut meal (HM) levels in juvenile rainbow trout (Oncorhynchus mykiss) diets on growth, feed consumption, and digestibility were investigated.Four experimental diets containing a gradient of HM (0%, 15%, 30% and 45% respectively) were prepared to feed two replicate groups of trout (initial body weight of 37.89±0.02g) twice daily to apparent satiation for 60 days.The highest weight gain rate (WGR) and specific growth rate (SGR) were obtained from the fish fed with Diet 1 and Diet 2 and it was determined that the increase of HM level in the diet up to 30% did not affect feed conversion ratio (FCR) and protein efficiency ratio (PER).The lowest WGR, SGR and PER were obtained from the fish fed with the diet containing 45% HM.The apparent digestibility coefficients (ADC) of protein (90.93-91.76%)and lipid (96.78-98.33%)were at high with no significant difference among treatment (P>0.05).The ADC of dry matter decreased with increasing HM in diets.These results indicated that HM can be utilized by 15% in diet for juvenil rainbow trout, without adverse effect on growth performance.