In the present investigation, genetic analysis for early growth traits of Sahiwal cows were performed using mixed linear model. The overall least squares means for body weights at birth (BW), 6 (W6), 12 (W12), 18 (W18), 24 (W24), 42(W30) months and weight at first service (WFS) were 20.59±0.27, 82.29±2.64, 136.98±3.26, 204.83±2.77, 252.27±3.24, 314.16±5.01 and 355.75±5.87 Kg, respectively. Effect of season of birth was non-significant on BW, W6 and W24 whereas season of birth significantly affected W12, W18 and WFS. The effect of period of calving of dams was significant on all growth traits under investigation except birth weight. Age at first calving of dams affected significantly all the growth traits of cows except birth weight. The estimates of heritability for BW, W6, W12, W18, W24, W30 and WFS were 0.117±0.18, 0.746±0.24, 0.587±0.23, 0.203±0.19, 0.230±0.20, 0.518±0.22 and 0.549±0.23, respectively.