Calorie restriction and starvation, as noted by some investigators, have antioxidant effect. It is necessary to disclose the metabolic effects beside functional effects of the short term fasting applied before elective surgical operations. This study was performed to investigate the effect of 48 hours of fasting on oxidant stress in rats. Totally 25 rats were fasted along 48 hours without water restriction. Blood samples were taken at the beginning, and at the 24th and 48th hours of fasting. Plasma malondialdehyde (MDA) levels were measured in those samples. Plasma MDA levels of the initial, 24th and 48th hours samples were 8.09±1.78, 6.86±2.51 and 4.47±1.62 nMol/ml respectively. In our study, 48 hours of starvation reduced oxidant stress increasingly. This reduction was manifested at the 48th hour. Also, it has been reported that starvation decreases the level of the glutathione and influences the antioxidant enzymes. Although, limited time of starvation has been accused of leading to increased free radical production in the presence of an oxidant stress source, it has antioxidant effect on basal conditions.