The external covering of egg is called eggshell. Chicken eggshell is composed of calcified egg shell as well as shell membrane. Its total weight is 10-11 % as compared to whole egg weight. Eggshell is an important structure for two reasons. Firstly, it act as an embryonic chamber during development of chick, secondly it act as a container and provide protection to the contents of egg and a unique container for the market egg. Despite its remarkable properties it is very often discarded from homes, restaurants, farms and factories. This review article aims to summarize the recent reports utilizing eggshell as calcium source in chicks, stressing the need to use a egg shell as a calcium source instead to use other sources. Hen eggshell is chemically composed of 65.6 % water, 11.8 % proteins, 11% fat and 11.7 % Ash. The shell consists of 97% calcium carbonate, and this is provided to the hen in the diet. However, the chemical must be broken down in the digestive system and then re-synthesized in the shell gland to form the shell. The shell of egg is the best sources of calcium then other sources like limestone. Calcium has an important role in formation of hard eggshell in hens. The calcium played a role in eggs quality as well as bone mineralization. Deficiency of calcium leads to minimize bone strength, egg weight and egg production.