A retrospective cohort study of mortality in the personnel of power-supply plants in the European regions of Russia was carried out. The exposure of the personnel to electromagnetic fields of power-line frequency (PF) was taken into account. Statistically non-significant raise of mortality from leukemia was found, compared to low mortality rates due to all other causes including cancer of any type. Standardized mortality ratio (SMR) was equal to 2.03 (95% CI = 0.23-7.31). In the retrospective case-control study the haemoblastosis development risk under occupational PF EMF exposure was evaluated. The data of 571 "cases" and 1208 "controls" interview showed that odd ratio (OR) was 1.64 (95% CI = 0.8-3.1). In another retrospective case-control study the risk of the haemoblastosis development in children due to parents PF EMF occupational exposure was evaluated. The data of 208 "cases" and 319 "controls" interview showed that the odd ratio (OR) was 1.69 (95% CI = 0.7-3.3). A retrospective cohort study of mortality in a settlement situated near a high-voltage (500 kV) substation, which took into account PF EMF levels in residential areas, revealed low mortality rates, except leukemia mortality (SMR 1.3; 95% CI = 0.2-7.0). The obtained data do not allow excluding a possibility of PF EMF leukogenic effect.