The objective was to determine the digestible tryptophan requirements for male broilers in pre-starter and starter phases. Two experiments using 400 Cobb broilers were performed 200 males in the first experiment for the pre-starter phase (one to seven days old), and 200 males in the second experiment for the starter phase (eight to 21 days old). Chicks were housed in batter boxes made of galvanized steel as an experimental shed. The experiments were performed in a completely randomized design, with four treatments and five replicates, with ten birds each. In both experiments, the tryptophan requirement was determined using diets with different levels of digestible tryptophan. A tryptophan-deficient diet was formulated, as a basal diet, which was supplemented with increased levels of L-tryptophan in order to achieve the desirable digestible tryptophan levels. Treatments consisted of 0.209% (basal diet); 0.223%; 0.235% and 0.248% digestible tryptophan for the pre-starter phase (experiment 1) and 0.187% (basal diet); 0.200%, 0.211% and 0.223% digestible tryptophan for the starter phase (experiment 2). We evaluated feed intake, weight gain and feed conversion, as well as the metabolizability of feed nutrients. The performance and metabolic data were subjected to analysis of variance, and estimates of digestible tryptophan levels were made through polynomial regression models at 5% probability. There was no significant difference between the digestible tryptophan levels in the diet over performance and digestibility in both treatments. It is possible to conclude that the basal diet with 0.209% digestible tryptophan for the pre-starter phase and 0.187% for the starter phase, at a tryptophan: lysine ratio of 16%, as sufficient to meet the broilers requirements. Key words: Animal nutrition. Chickens. Digestible amino acid. Digestibility. Performance. ResumoObjetivou-se determinar as exigências de triptofano digestível para frangos de corte machos nas fases pré-inicial e inicial. Foram realizados dois experimentos utilizando 400 frangos de corte da linhagem Cobb, sendo o experimento 1 com 200 machos para a fase pré-inicial (um a sete dias de idade), e o 1 M.e em Ciência Animal, Escola de Medicina Veterinária e Zootecnia, EVZ, Universidade Federal de Goiás, UFG, Goiânia, GO,Brasil. E-mail: brunozootecnia22@hotmail.com 2 Profs., Pós-Graduação em Zootecnia, EVZ/UFG, Goiânia, GO, Brasil. E-mail: romaocnunes@hotmail.com; jhstring@uol.com. br; alegimenez09@hotmail.com; heloisamello@gmail.com 3 Discentes do Curso de Doutorado em Zootecnia, EVZ/UFG, Goiânia, GO, Brasil. E-mail: julyanamachado_zoo@hotmail.com; raianazoo@hotmail.com; mary_zoo@hotmail.com * Author for correspondence experimento 2 com 200 machos para a fase inicial (oito a 21 dias de idade), alojados em baterias, contendo gaiolas de arame galvanizado, em um galpão experimental. Os experimentos foram realizados em delineamento inteiramente casualizado, divididos em quatro tratamentos, com cinco repetições e dez aves por repetição, sendo que cada repetição com...