This retrospective study has been performed with radiation victims who were accidentally exposed to a Co-60 source and its release into the environment. The aim of the study was to assess the effects of elevated radiation exposures on plasma level, on erythrocyte thio barbituric, acid reactive substance (TBARS) level and on erythrocyte glutathione (GSH) levels. Patients were treated in different hospitals with different symptoms such as nausea, vomiting, dizziness, along with severe anemia in some patients. Blood samples were collected 3-5 days following the radiation accident. Increases in plasma (6.25 +/- 0.90 nmol ml(-1)) and erythrocyte TBARS levels (330.5 +/- 30.5 mumol gHb(-1)) were found in comparison to a healthy group (3.72 +/- 0.68 nmol ml(-1) and 150.7 +/- 20.5 mumol gHb(-1), respectively) at a significant level (p<0.001). Erythrocyte GSH levels (5.2 +/- 0.30 mumol gHb(-1)) were found to be decreased among the victims (healthy-group: 10.2 +/- 0.7 mumol gHb(-1)) at the same significance level (p<0.001). These observations confirm a significant change induced by radiation in the oxidant/antioxidant status among the victims. It is suggested here that antioxidant supplementation therapy might be effective. in preventing the harmful effects of Co-60 radiation among radiation victims. (C) 2002 Elsevier Science Ltd. All rights reserved.