Age-weight data of 1150 Barki sheep (600 females and 550 males) progeny of 60 sires and 850 dams were fitted to Brody growth function to estimate body weight at maturing. Genetic and phenotypic parameters for body weights at birth (W₀), weaning (W₀₄), 8-month (W₀₈), yearling (W₁₂) and maturity (W_M) were estimated using a multi-trait animal model including the fixed effects of sex of lamb, year of birth and age of dam and the random effects of direct genetics. The estimated parameters were used to construct seven selection indexes aiming to improve marketing body weights W₀₈ and W₁₂ , representing the aggregate genotype, with minimum changes in W_M. From the standpoint of accuracy, the full index (I₁ = 2.69  W₀ -  0.977 W₀₄ + 0.909 W₀₈ + 0.433 W₁₂)had the highest correlation with the true breeding value (r_TI = 0.74) followed by late selection (r_TI = 0.56 to 0.62) then early selection (r_TI = 0.26 to 0.33). Use of I₁ should result in developing sheep with W₀ (0.14 kg), W₀₄ (0.51 kg), W₀₈ (1.72 kg) and W₁₂ (2.08 kg), provided an increase of 1.36 kg in W_M would be accepted. If not, two restricted selection indexes were recommended viz., I_(WM) and I_(W0). The index I_(WM) = -2.508 W₀   -0.228 W₀₄ +0.396 W₀₈ + 0.020 W₁₂, would reduce the expected increase to zero in W_M and to essentially zero in W₀, but at the cost of reducing selection accuracy excessively (r_TI = 0.30) and limiting improvement in marketing weights (0.67 and 0.87 kg). The index I_1(W0)  = -2.764  W₀ -  0.391 W₀₄ + 0.477 W₀₈ + 0.342 W₁₂, representing a good compromise, would lead to only 0.55 kg increase in W_M and zero increase in W₀ together with more acceptable improvement in marketing weights (1.18 and 1.48 kg).