Aim of the present study was to evaluate the effect of  replacing yellow corn with different levels of discarded dates in concentrate feed mixture on, feed intake, growth performance, feed conversion, carcass characteristics and economic feed efficiency of fattening Friesian calves.  Twenty male Friesian calves (241.20±2.14 kg and 11 mo of age) were randomly assigned into four groups (five in each). Discarded dates (DD) was used in partial replacement of yellow corn grains (YCG) (w/w) in concentrate feed mixture at levels of 0% (G1), 33% (G2), 66% (G3) and 100% (G4), respectively. Results showed that DD contained higher CF, ash, lucien, isolucien, lysine, methionine, cysteine and histidine contents and lower OM, CP and NFE contents compared with YCG. All DD--diets slightly increased  feed intake up to 66% DD. Final body weight, total and daily weight gain, and relative weight gain were higher (P<0.05) in G2 and G3 than in G4 and G1. Feed conversion improved (P<0.05) with increasing DD level up to 66% in G2 and G3. Average weights of pre-slaughtered animals, hot carcass, and boneless meat were higher (P<0.05), while weight and percentage of bone decreased (P<0.05) in G2 and G3 as compared to G1 and G4. The highest percentages of dressing and boneless meat was in G2, followed by G3, while G1 and G4 showed the lowest (P<0.05) percentages. Ribcut weight was higher in G3 and G2 than in G1 and G4. Percentage of lean, fat and bone was higher in G2, followed by G3, G4 and G1, respectively. Economic feed efficiency was higher for calves in G2, G3 and G4 by 19.44, 30.56 and 21.53% compared with those in G1 (control group), respectively. The current study concluded that dietary incorporation of discarded dates up to a level of 66% instead of yellow corn had impact on growth performance, carcass traits and economic feed efficiency of fattening calves. In addition, using discarded dates as by-products in ruminant diets could be useful in reducing the environmental pollution in Egypt.