EElectromagnetic radiation has been reported to induce toxicity to many organs of the human body. Electrical substations and cellular communication towers are important sites which emit a continuous electromagnetic radiations of wide spectrum. Radiation is one of the important exogenous sources of free radicals and reactive oxygen species (ROS), which can cause oxidative stress. While elevated ROS cause oxidative damage, the antioxidants are able to reduce these toxic effects. We have aimed to investigate the oxidative stress, antioxidant and thyroid function in the serum of workers at electrical substations and cellular communication towers. The study was included 40 men from electrical substations, 40 men from cellular communication towers, and 40 men from sites away from these two foundations used as control for the study. Total oxidant status (TOS) and malondialdehyde (MDA) were evaluated as oxidative stress markers, while total antioxidant capacity (TAC) and glutathione (GSH) were evaluated as antioxidant markers. The thyroid function was determined by evaluating thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4). The results have shown significant (P<0.05) elevated levels of TOS and MDA encountered by significant reduced levels of TAC and GSH in the serum of electrical substations and cellular communication towers workers. The most significant alteration was seen in the serum of electrical substations workers. Thyroid function was observed to be normal in both electrical substations and cellular communication towers workers, despite that TSH was significantly higher in electrical substations workers compared to the other two groups.