The aim of the study was to estimate the effect of static electric fields with physical parameters generated nearby HVDC transmission lines on hormonal system of experimental animals. 96 male Wistar rats were exposed for 56 consecutive days (8 hours daily) to static electric field with intensity of 16, 25 and 35 kV/m respectively, while 32 control rats were shame-exposed. Exposure to static electric fields evoked transient stimulation of insulin and thyroid hormones secretion as well as decrease in serum corticosterone level. As observed effects appeared mostly for intensity above 16 kV/m in prepared recommendations potential harmful effect of electric fields with such intensities should be regarded.