Energy utilization in broilers as influenced by supplementation of enzymes containing phytase or carbohydrase activities was investigated. Day-old male broilers (480) were allocated to four slaughter groups, thirty broilers in the initial slaughter group and 150 broilers in each of the final slaughter groups on days 7, 14 and 21. Broilers in each of the final slaughter groups were allocated to five treatments in a randomized complete block design, each treatment had six replicate cages of five broilers per replicate cage. The diets were maize-soyabean based with wheat as a source of NSP. The treatments were: (1) positive control that met nutrient requirements of the day-old broiler chick; (2) negative control (NC) deficient in metabolizable energy and P; (3) NC plus phytase added at 1000 FTU/kg; (4) NC plus cocktail of xylanase, amylase and protease (XAP); and (5) NC plus phytase and XAP. Gain and gain:food were depressed (P < 0.05) in the NC diet. Phytase improved (P < 0.05) gain at all ages and gain:food at days 0-14 and days 0-21. There was improvement (P < 0.01) in net energy for production, energy retained as fat and protein from days 0 to 14 and from days 0 to 21 in phytase-supplemented diet compared with the NC diet. Net energy for production was more highly correlated with performance criteria than metabolizable energy and may be a more sensitive energy utilization response criterion to use in evaluating broiler response to enzyme supplementation.