Parameters of the Gomperz function pf growth fit to individual body weight curves of two crossbred groups. Six hundreds and twenty chicks from two groups were used. The first group involved Fayoumi (Fay), Rhode Island Red (RIR) and their reciprocal crosses (FayxRIR) and (RIRxFay). The second group involved Sinai (S), White Leghorn (WL) and their reciprocal crosses (WLxS) and (SxWL). The objective of this research was to evaluate the growth pattern of local and crossbreds chickens and to evaluate growth curve parameters using non-linear model for Gompertz. Chickens were weighed at hatch, 14, 21, 30, 45, 60, 90, 124 and 154 days of age. Feeds and water were supplied ad libitum. In the first group: weights at 16 week of age relative to asymptotic was the same for (FayxRIR) and (RIRxFay) and highest for Fay and RIR. Birds in (FayxRIR) showed the lowest maturing rate 0.3365 for female and 0.3386 for male. High estimates for mature weight were observed in (FayxRIR) males and (FayxRIR) females. The mature live weights of hybrid (FayxRIR) males was 3.370 Kg compared to 2.680 kg for (RIRxFay). The rate of maturing parameters (L) of the males used in this evaluation was greater than for the females. In the second group: (WLxS) chicks were hieavier the Sinai and (SxWL) chick at hatch. (WLxS) hybrid was heavier at 12 week of age than (SxWL), S and WL. Both hybrids reached the same asymptotic body weight at 20 week of age. The predicted mature body weights differ among sexes. The rate of maturation K was higher in males than in females. The mature body weight estimated for males were higher than those for females.