The objective of the research study was to assess the content of some chemical components in hen eggs from four laying hen breeds covered by the genetic resources conservation programme, depending on the egg production cycle. The research material consisted of eggs from: Greenleg Partridge (Z-11), Yellowleg Partridge (Ż-33), Sussex (S-66), Leghorn (G-99) as well as from Hy Line Brown commercial laying hens. The laying hens were kept on a farm at the Experimental Station, National Research Institute of Animal Production in Chorzelów near Mielec. The chemical analyses of eggs were performed in the 33^rd and 83^rd week of the age of hens. The highest content of total protein and mineral compounds in the form of crude ash was found in the eggs laid by the Hy-line Brown hens in their 33^rd week of age and in the eggs laid by the S-66, G-99, and Hy-Line Brown hens in their 83^rd week of age; the latter also had the highest level of dry matter and the highest level of crude ash. The highest content of total protein was determined in the yolks in the eggs produced by the Z-11 and Ż-33 hens of the conservation breeds, especially in the second year of production. A significantly lower content of protein was reported in the yolks in the eggs laid by the G-99 and Hy-Line Brown hens in their 33^rd and 83^rd week of age. The yolks in the eggs laid by the S-66 laying hens had the highest concentration of fat, which tended to increase along with the age of the hens. The level of cholesterol ranged from 13.90 to 14.78 mg/g of yolk in the 33^rd week of age and from 14.29 to 15.48 mg/g of yolk in the 83^rd week of age, whereas the Z-11 hens produced eggs with the lowest percent level of cholesterol compared to all other hen breeds. A high content of nutrients assayed in the second production cycle proves that it is reasonable to utilize all the hen breeds studied during a period of at least one year and a half.