three hundred and eighty-four birds, half males and half females, were used to determine the copper (cu) requirement for broilers in the initial phase (from 8 to 21 days). a basal diet was formulated to meet the bird nutritional requirements, except for cu, that was deficient at 1.47 ppm level. the treatments consisted of cu supplementation levels, from cu sulfate, in a total of 1.47, 4.97, 8.47, 11.97, 15.47 and 18.97 ppm cu in the diet. weight gain, feed intake, feed:gain ratio and cu concentration in the bone, liver and serum were evaluated. the studied cu levels affected feed intake, but did not alter weight gain and feed:gain ratio. no effects of cu levels on cu concentration in the bone were detected. effects of increasing dietary cu levels on cu concentration in the liver and serum were observed. however, the most adequate value of cu requirement was estimated in the serum, because it better represents the cu nutricional status in the animal organism. it was concluded that cu requirements for broilers, males and females, from 8 to 21 days old is of 9.48 ppm, considering that corn and soybean meal-based diets, for broilers, contain from 8.5 to 11 ppm cu and that cu bioavailability in the soybean meal of 38%.