We used mixed linear regression analysis to model tree size and yield of eight apple rootstocks grown in Minnesota using data collected over several trials and years to compare rootstock performance. The model accounted for a significant portion of the variation in trunk cross-sectional area and yield but substantial variation remained unexplained. The model estimated that the largest trees were on G.30 followed by V.1, M.7, M.26, V.3, M.9, G.16 and Bud.9. Estimated yield was greatest for V.1, followed by G.30, G.16, M.9, M.26, V.3, B.9 and M.7. Based on this analysis G.16 had the highest yield efficiency in Minnesota followed by V.1, M.9, V.3, G.30, M.26, Bud.9 and M.7 which had the lowest yield efficiency.