The changes in some factors of the innate immunity (phagocytosis, complement, lysozyme); haematological parameters-leukocytes, erythrocytes, differential white blood cell counts, haemoglobin, haematocrit and the serum concentrations of the microelements zinc and iron in six 2- to 3-months-old female piglets after the intravenous administration of lipopolysaccharide from Escherichia coli 0111:B4 were determined. It was found out that 1 h after the administration of lipopolysaccharide at the dosage rate of 10 microg/kg body weight resulted in a decrease in the phagocytic parameters, i.e. the phagocytic number and the index of phagocytic activity, which was followed by an increase in their values between post treatment hours 2 and 4. The leukocyte counts had decreased by hour 2 after the injection, but thereafter increased, and at post treatment hour 72, a leukocytosis was observed. The differential white blood cell counts were characterized by a shift to the left between hours 2 and 4 and a statistically significant increase in lymphocyte counts at hour 48 of the experiment. The serum zinc concentrations were increased an hour after the lipopolysaccharide application; after which their average values were lower. The haemolytic activities (CH50) of the classical and the alternative pathways of complement activation decreased. The haemolytic activity (CH50) for the classical pathway began to increase at hour 48 following the treatment. Significant changes were not observed in lysozyme activity, serum iron concentrations or the related haematological parameters (erythrocytes and haemoglobin).