ABSTRACT The purpose of this study was to evaluate the effect of green monochromatic light emitting diodes (LED) or white fluorescent lamps on the growth performance of broilers reared in open houses. Two hundred broilers (Ross 308) were sexed and divided into four treatments, according to sex and supplemental light source: T1, males under green LED; T2, males under fluorescent lamps; T3, females under green LED; and T4, females under fluorescent lamps, totaling 50 birds per treatment with five replicates each (n=10). Broilers of both sexes received natural light during the day and supplemental lighting (fluorescent or LED) during the night, according to age. Individual body weight, mortality, and feed intake were recorded weekly per replicate. Feed conversion ratio and the European Efficiency Index (EEI) were calculated. Data were analyzed by a two-way ANOVA. The results indicated differences (p< 0.05) in female body weight in week 6, (2202.31 ± 32.93g green LED vs 2191.08 ± 62.13g fluorescent lamp), but no differences in daily weight gain, feed conversion ratio, or mortality were detected. However, the use of green LED promoted higher EEI in males in weeks 5, 6, and 7, and in females in week 5 (p < 0.05). Green monochromatic LED may be used for supplemental lighting of male broilers reared in open houses with natural light. Its use for female broilers is recommended if the birds are marketed up to 5 weeks of age.