The aim of the study was to determine the changes in the content of major proteins, glucose and selected hormones in the blood of piglets during the first 7 days of neonatal life. The study involved an entire litter of eight newborn piglets of F1 hybrids (Polish White Large x Polish Landrace) delivered from one sow in the second gestation. In blood samples collected directly after parturition (before colostrum intake), in the 12th, 24th and 48th hour and in 7th day of life, the content of total protein and its fractions, glucose concentration and the level of insulin, T3 (total and free), T4 (total and free), leptin, resistin and ghrelin (total and active) was determined. In the blood serum of newborn piglets a low content of total protein, albumins, gamma globulins and a high share of alpha- and beta globulins was found. In the 12th hour of life, after colostrum intake, a significant (P<0.05) increase in the content of total protein, albumins, beta-globulins and a rapid increase of gamma globulins as well as decrease of alpha-globulins level were observed. In the consecutive periods of postnatal life a significant (P<0.05) decrease of total protein, beta- and gamma globulins as well as a steady increase in the content of albumins in the blood serum of piglets was observed. The content of glucose, insulin, leptin, resistin and ghrelin in the blood serum of neonates increased significantly (P<0.05) after colostrum intake. During the successive experimental periods a progressive increase (P<0.05) of glucose and T3 as well as systematic decrease of insulin, T4, ghrelin and resistin in the blood serum was observed as compared to the 12th hour of life.