A crossbreeding experiment was executed between the local strain of Golden Montazah (GM) and a standard breed of White Leghorn (WL). Data of 5029 chicks were produced by 79 sires and 441 dams from five genetic groups (two foundations of GM and WL, three crossbreds of GM x WL, (GM × WL)2 and ((GM× WL)2)2. Body weight of these chicks were individually recorded in grams at hatch (BW0), 4 (BW4), 8 (BW8), 12 (BW12) and 16 (BW16) weeks of age. Daily gains in weight (grams) during the age intervals of 0-4 (DG4), 4-8(DG8), 8-12(DG12) and 12-16(DG16) weeks were calculated. Single-trait animal model analysis was used to analyze the data of body weight and daily gain traits. Results showed that GM strain had superiority (p<0.05) in most of the studied traits compared to WL, except BW0. Averages of most of the traits studied in crossbreds were higher than purebreds. Percentages of direct additive effects were mostly negative and highly significant (P<0.01) and ranged from -14.29 to 2.51% for body weights and from -21.13 to 6.74% for daily gains in weight. Estimates of direct heterosis (HI) were positive and highly significant (P˂0.01) for most of the traits studied. Percentages of HI ranged from -12.18 to 17.87% for body weights and from 8.12 to 25.30% for daily gain traits. Estimates of maternal heterosis (HM) were negative and highly significant (P˂0.01) for most of the traits studied. Percentages of HM ranged from -8.93 to 5.36% for body weights and from -14.18 to 32.96% for daily gain traits. It is concluded that crossing of GM with WL are recommended to improve growth traits of chickens in Egypt.