Weights and individual feed intake data of 30 Dorper crossbred ewes and their single-born lambs were collected from conception to weaning. The data were used to calculate actual weaning efficiency of the individual ewe-lamb units [AEFF = lamb weaning weight/DDMI (digestible dry matter intake) of both ewe and lamb x 100]. The accuracy of ewe weight (EWb) as a predictor of lamb weight (LW) and of predictive weaning efficiency (PEFF = LW/EWb) as a predictor of AEFF were investigated. Best predictions were obtained when EW was raised to the power of 0.72 and 0.67, respectively.