Abstract: This study was conducted to investigate the effects of dietary dried baker�s yeast on growth performance, feed utilization and feed ingredients digestibility of koi carp (Cyprinus carpio L., 1758) fingerlings. In the experiment, a total of 270 koi carp fingerlings were equally divided into six groups of 45 (three replicates of 15 koi carp fingerlings each). Six levels (0, 10, 20, 30, 40 and 50%) of Dried Baker�s Yeast (DBY) were included in isonitrogenous and isocaloric diets. The experimental period lasted 2 months (4 fortnight period). At the end of the experiment, there were no significant differences among the groups of 0, 10, 20, 30% in Body Weight (BW), Feed Intake (FI), Protein Intake (PI), Feed Conversion Ratio (FCR) and apparent digestibility (p>0.05). The inclusion of DBY at the level of 40% to the diets reduced Weight Gain (WG), FCR, Specific Growth Rate (SGR), Protein Efficiency Ratio (PER) and apparent digestibility (p<0.05). The highest dry matter, protein, fat, fiber, ash, nitrogen free extract and organic matter digestibility coefficients were observed in fish fed diet T (control diet 0% dry yeast replacement) which were significantly higher than those observed for the other diets (p<0.05). It is concluded that DBY can be used up to 30% in the diets of koi carp fingerlings without adverse effects on the measured parameters.