The present study was undertaken to investigate the effects of feeding urea-containing grower diets on growth performance, nutrient digestibility, carcass traits and some blood parameters of broiler chicks. Three hundred sixty 3-wk-old unsexed (Cobb-500) broiler chicks were randomly divided into five equal treatments; each consisted of 6 equal replications, and kept in conventional wire-floored growing batteries. Five experimental diets [of similar crude protein (18.9%) and metabolizable energy (about 3136 kcal/kg) contents] having five graded levels of urea (0.00, 0.345, 0.69, 1.035 and 1.38%) were formulated and used from 3 to 6 weeks of age. All birds had free access to feed and water and were reared under similar managerial and environmental conditions. The response of chicks to feeding the urea-containing diets included growth performance [in terms of feed intake (FI), live body weight (LBW), body weight gain (BWG), feed conversion (FC), economic efficiency of growth (EEG), mortality rate, nutrient digestibility [including dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), crude fiber (CF) and nitrogen-free extract, and ash and nitrogen retention], certain carcass traits, and some blood parameters. The obtained results could be summarized as follows: There were significant depressions in final LBW, BWG and FI of birds fed the urea-containing diets as compared to their control group; however, FC and EEG were not significantly affected. With the exception of slight reductions in crude protein digestibility and rate of nitrogen retention in birds fed the 1.38% urea in their diet while the other experimental groups (fed diets containing 0.345, 0.69 and 1.035% urea) exhibited means of digestibility for DM, OM, EE, CF and NFE as well as ash retention comparable to those of the control birds. Feeding the urea-containing diets had no significant effects on either carcass traits or blood parameters but urea concentrations in blood plasma of broilers fed the diets containing 0.69, 1.035 and 1.38% urea were significantly higher compared with their control counterparts. Because of the depressed growth performance and poor economic efficiency of growth resulting from feeding the urea-containing diets, it can be concluded that urea addition as a source of non-protein nitrogen in broiler chick diets is nutritionally invaluable and not recommended.