Dichlorodiphenyltrichloroethane (DDT) and its metabolites are constantly detected in agricultural crops intended for animal feed. The aim of this study was to evaluate the impact of DDT residues in feed on thyroid gland and liver secretory activity of Aberdeen-Angus cattle depending on cattle age and sex. DDT (sum) concentration in the forage (milk, hay, silage, compound feed) and soil was determined by gas chromatography with micro electron capture selective detector (GC/ECD), while thyroid gland hormones (triiodothyronine (T3), thyroxine (T4)) concentrations and liver enzymes (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatine kinase, lactate dehydrogenase) activities using ELISA, based on colorimetric method. It was indicated that natural contamination of soil and, in consequence, feed with DDT is diversed and was the highest in milk. Concentration of T3 decreased during bulls growth reaching the lowest level in 8-month animals (1.92 pmol/l), while content of T4 was raising and achieved the highest content in 8-month bulls (129.07 pmol/l). Opposite relation was observed in heifers (increasing content of T3 and falling level of T4). Liver enzymes activity was also depended on cattle age and sex. However, concentrations of thyroid hormones and activities of liver enzymes were significantly higher (P < 0.05) in bulls and heifers fed forage containing DDT. DDT contamination of feed leads to hypothyroid in bulls and hyperthyroid in heifers in long-term intake. Milk, which is given to the calves at the beginning of the nursing period should be especially examined for DDT residues occurrence because young animals are particularly susceptible to endocrine and liver disorders.