The fast economic development has polluted the environment and led to a remarkable global warming worldwide characterized by an environmental hyperthermia. In view of these circumstances, the investigation of some biological markers during the combined stress was carried out. Thus, the effect of heat stress (HS), cadmium chloride (Cd) and heat stress-cadmium (HS-Cd) were performed on Wistar rats for a period of 8 consecutive days. The control and the cadmium group (10 mg cadmium chloride daily by gavage) were housed separately (temperature ranges 22.23-25.45 °C). The HS and HS-Cd groups were placed in a thermal chamber where they exposed each day from 09:00h to 13:00h (temperature ranges 34.41-37.23 °C). However, serum total proteins, sodium, chlorine, calcium, potassium and blood components were investigated. The obtained results showed a remarkable increase of serum Na in HS-Cd and serum Cl in HS and HS-Cd were seen. However, in the cadmium treated group, only calcium level was affected by a notable decline after one week. In the combined treatment, the concentrations of serum calcium as well as that of serum total proteins were decreased significantly. Contrary, serum K was within normal ranges in all treated groups. RBC and WBC counts were remarkably lower in the HSCd group, while hematocrit was significantly decreased in all treated groups. To conclude, the combined stress has made deep alterations on biological markers of Wistar rats.