The aim of this study was to compare estimation methods: least squares method (LS), ridgeregression (RR), Principal component regression (PCR) to estimate the parameters of multipleregression model in situations when the underlying assumptions of least squares estimation areuntenable because of multicollinearity. For this aim, the effect of some body measurements on bodyweights (height at withers and rumps, body length, chest width, chest girth and chest depth, front,middle and hind rump width) obtained from totally 85 Karayaka lambs at weaning period raised atResearch Farm of Ondokuz Mayis University was examined. Mean square error, R2 value andsignificance of parameters were used to evaluate estimator performance. The multicollinearity,between front and middle rump width which were used to estimate live weight, was eliminated byusing RR and PCR. Although research findings showed that RR method had the smallest MSE andthe highest R2 value, the estimates of PCR were determined to be more consistent when theimportance tests of parameters were taken into account. The results showed that principal componentregression approach should be used to estimate the live weight of Karayaka lambs at weaning period.