This study was conducted to determine the optimum dietary glycine equivalent (Gly_equi) level in low-crude-protein diets of 181 g·kg⁻¹ containing varied concentrations of standardized ileal digestible (SID) methionine + cysteine (Met + Cys) for broiler chicks (1–21 d old). A total of 1275, 1-d-old Cobb-Vantress^® male broilers were distributed in a 5 × 3 factorial arrangement with a completely randomized design of 15 treatments with five replicates of 17 birds each. Treatments consisted of five levels of dietary Gly_equi (14.9, 16.4, 17.9, 19.4, and 20.6 g·kg⁻¹) and three concentrations of SID Met + Cys (7.70, 9.0, and 10.3 g·kg⁻¹). Interactions between Gly_equi and SID Met + Cys levels were observed for feed:gain (P = 0.055) and breast meat yield (BMY) (P = 0.017). In 7.7 and 9.0 g SID Met + Cys·kg⁻¹ diets, optimal feed:gain and increased BMY were observed at Gly_equi levels not lower than 17.9 g·kg⁻¹. In 10.3 g SID Met + Cys·kg⁻¹ diet, a lower feed:gain was achieved at 19.4 g Gly_equi·kg⁻¹. Therefore, a minimum dietary level of 17.9 g Gly_equi·kg⁻¹ is needed to increase growth of broilers fed diets containing 7.7 or 9.0 g·kg⁻¹ SID Met + Cys, whereas 19.4 g·kg⁻¹ Gly_equi is necessary in diets containing 10.3 g·kg⁻¹ SID Met + Cys for optimum growth.