In this study, we investigated the effects of High Voltage Transmission Lines (HVTL) on people who work and live in such areas. The study was carried out on 51 persons from 15 to 50 years of age exposed to electric field. First, we gave out a questionnaire to everybody under investigation. We established that these people most often suffer from headache, irritability, fatigue, stress and shock. Secondly, we determined 23 parameters of their blood serum. The levels of ALP, Na, Cl, total protein, albumin, Group Specific Component, ceruloplasmin and albumin/globulin ratio were found especially significant.