Pillar systems in mines are statically indeterminate systems. The paper presents the results of numerical investigations to evaluate the effects of panel dimensions on pillar loads. It is shown that pillar load in deep mines is strongly influenced by the lateral and vertical extent of extrac-tion panels. The commonly applied tributary area concept does not account for these effects and is an oversimplification that has to be applied with caution. The effects of local pillar fail-ures on stability of pillar workings are examined using simple models. It is shown that limiting panel dimensions by substantial barrier pillars can reduce the danger of regional pillar collaps-es and enhance overall mine stability.