The exact knowledge about the optimal ratio between true digestible (TD) Valine to Lysine for broiler chicks is very important for further reductions of protein. The following study proves the impact of an increasing TD V:L ratio in a protein reduced diet on the growth and slaughter performance of broiler chicks. 345 eight day old chickens (Ross 308; 1210.9 g) were randomly divided into 24 pens and 5 dietary treatments. The trial was split in a grower period until live day 21, and a finisher period until the end of the study (live day 36). Grower diets (13.0 MJ AMEN; 18.5% CP) and finisher diets (13.1 MJ AMEN; 15.7% CP) based on corn and soybean meal respectively. Lys was adjusted to act as second limiting amino acid (grower: 10 g TD Lys/kg, finisher: 8 g TD Lys/kg). All other essential amino acids were orientated on the ideal protein. The ratio of TD V:L in the diets increased from 68%; 73%; 78%; 83% to 88%. The chicks were fed and watered ad libitum. Parameter of performance were analysed by ANOVA (P<0.05). The feeding groups with higher TD V:L ratio were significantly different due to the ratio with 68%, which had the worst performance. In the parameter daily live weight gain there was a significant (p<0.05) continuous progress up to 83% TD V:L in grower (41 g) and finisher (77 g). Also in the parameter daily feed intake there was a significant (p< 0.05) difference between the diets with higher TD V:L ratio in grower and finisher phase due to the diet with 68% TD V:L. All the other growth performance parameters indicate, that the ratio with 78% and 83% TD V:L had the best performance. The slaughter parameters showed also an improved performance with higher Val to Lys ratio in the diet. The diet with 83% TD V:L had the heaviest weight at the parameter eviscerated carcass and on the carcass for grilling. The best performance was shown in the diets with 78 and 83% TD V:L. It can be suggest, that the optimal ratio between TD V:L seems between 78% and 83%.