Guanidinoacetic acid (GAA) spares L-Arginine (Arg) when supplemented in the diets of broilers as less Arg would be required to synthesise creatine for which GAA is a precursor. In chickens, Lcitrulline (Cit) can also be converted to Arg by the successive actions of two enzymes, argininosuccinate synthetase and argininosuccinate lyase in the kidney and other extrahepatic tissues (Dao et al., 2021). Data are sparse for comparing the effectiveness of GAA and Cit individually or in combination for replacing dietary Arg in broiler chickens. Using a completely randomised design, a 42-day study was conducted with 9 dietary treatments for grower (d 10 to 24) and finisher (d 24 to 42) phases. The first three diets included a control diet (T1) supplemented with 0.24% Arg and two semi-deficient and deficient diets that had 0.12% (T2) and no added (T3) Arg, respectively. Treatments 4, 5 and 6 were constructed by replacing 0.06% of Arg with 0.06% GAA (T4), 0.06% Cit (T5) and a combination (T6) of GAA and Cit, equivalent to 0.12% Arg. Treatments 7, 8 and 9 were made by replacing 0.12% of Arg with 0.12% GAA (T7), 0.12% Cit (T8) and a combination (T9) of GAA and Cit equivalent to 0.24% Arg. Both GAA and Cit replaced Arg at one to one ratio without any uplift designated for their energy contributions in the formulation matrix. Grower and finisher diets contained crude protein levels of 19.6% and 18.2% and digestible Arg of 1.28% and 1.18%, respectively. For the first 10 d of age, all birds received a common starter diet. A total of 864 day-old male off-sex Ross 308 chicks were assigned to 72 pens each accommodating 12 birds. Each diet was replicated 8 times.