The aim of the study was to determine the changes in the selected biochemical serum parameters in male Ross 308 broilers during the fattening period. The birds were kept under standard farm conditions and they were fed on commercial mixtures. The blood for analysis was taken from the jugular vein on the 14th, 21st, and 42nd days of age. The concentration of serum protein (total protein, albumins, uric acid, creatinine), lipid (TG, TCHL, HDL) and mineral (Ca, P(i), Mg, Fe) indices were determined. The measurements were carried out with the use of Epoll 20 photometer. The content of LDL and VLDL lipoprotein fractions was calculated on the basis of the Friedewald equation. Most of the estimated parameters, except for LDL and Pi, were age-dependent (P<0.05). Total protein, albumins and total Ca levels showed a constant increase between the 14th and 42nd days of life. A lower (P<0.05) concentration of TG, TCHL, HDL, VLDL, Mg and Fe was determined at the end of the fattening period compared to 14-day-old broilers. A significant decrease of TG, VLDL, Mg and Fe content was noted already in the first age range (days 14-21) while in the case of TCHL and HDL a significant decrease was found between the 21st and 42nd days of fattening. The obtained results may be helpful in the evaluation of changes in the metabolic profile, health condition and production patterns in growing broiler chickens reared under farm conditions.