Calcium is the most important and the most abundant mineral in the egg shell of laying hens. The source and the digestibility of calcium have the most impact on the hardness of the egg shell. Its low quality is the main source of losses in the production of the eggs, especially among older laying hens. It is well known fact that the digestibility of calcium is better from coarsely rather than from finely ground egg shell, but the same digestibility of calcium is not known between finely and medium coarsely ground egg shell. As the coarsely ground shell is unevenly distributed in complete mixtures for laying hens the objective of this study was to determine the digestibility of calcium that comes from food with total or half limestone replacement for finely and medium coarsely ground egg shells in older laying hens. The research on the digestibility was conducted on 75 Hissex-brown laying hens at the age of 75 weeks during the last 28 days of the laying. Laying hens were distributed in five treatments with five repetitions on three hens in every repetition. The small egg shell was 3,76 times smaller than the medium large egg shell (0,15:0,56 mm). The research revealed that the older laying hens digest calcium at their worst when it comes only from limestone (32,68%:42,60%). Although a significant difference in the digestibility among individual treatments was determined there was no difference in the digestibility of calcium between complete and half origin from the egg shell and limestone (42,7%:42,5%) as well as between the small and the medium large egg shell (42,4%:42,8%). There is no difference in the digestibility of calcium between medium and finely ground egg shell.