This study determined effects of birth weights(0.70 to 1.09, 1.10 to 1.49, 1.50 to 1.89,and ≥ 1.90 kg)on the efficiency of milk utilization for growth in sow-reared piglets. One-hundred-sixty piglets from 18 multiparous sows(Landrace x Large White)were individually weighed immediately after birth(day 0)and at 7-day intervals for 35 days. Milk consumption of piglets was determin .ed weekly using the weigh-suckle-weigh method. Deaths of piglets were recorded daily. Piglets with the lightest birth weight had the highest incidence of mortality. Birth weights between 0.70 and 1.89 kg were positively as-sociated with average daily gains(ADG, g/day)during the suckling period(P < 0.01). Compared with piglets having birth weights of 1.50 to 1.89 kg,birth weights ≥ 1.90 kg did not confer any additional benefit on preweaning survival or ADG. Colostrum or milk consumption per kilogram of body weight among low-, normal-, and large-birth-weight piglets did not differ in the first week. At days 14 to 35, milk consump-tion of piglets(g/kg BW/day)increased(P < 0. 01)but the ratio of gain to milk consumption decreased (P < 0.01)progressively, as their birth weights in-creased from 0.70 to ≥ 1.90 kg. Additionally, survi-ving low-birth-weight piglets had a higher relative growth rate(%/day)than normal-and large-birth-weight piglets. Based on these novel findings, it is imperative that great efforts be made to improve the survival of low-birth-weight piglets so as to increase the efficiency of nutrient utilization by both lactating sows and suckling piglets.