Selenium (Se), an essential micronutrient of several major metabolic pathways, including thyroid hormone metabolism, antioxidant defense systems, and immune function becomes toxic to animal when it is elevated above a threshold concentration. The aim of the present study was to determine the effect of selenium in rats Wistar albino on plasma levels of cholesterol, triglycerides, urea, uric acid, albumin and calcium. The experimental groups received subcutaneously graded doses of Selenium (0.3 and 0.5 mg/kg, BW) for a period of 21 days and plasma biochemical parameters were evaluated after 3, 6 and 21 days. The results indicated that the graded doses of Selenium significantly decreased both the calcium and plasma cholesterol level during short-term and long-term respectively. On the other hand, Se elevated significantly the levels of plasma urea by 104% after the first three days, uric acid by 126%, on day 6 and triglycerides by 120% on day 21. Whereas, the higher dose increased the level of plasma urea only on day 21 by 67%. Furthermore, 0.5 mg s.c provoked an immediate and a significant increase in plasma cholesterol level by 47% and in uric acid by 60% during the first three days after treatment. Doses of Se augmented significantly on day 6, the level of plasma albumin by 85% and 52 % respectively. The results of the current study suggested that selenium alters the plasma biochemical parameters in rats. Keywords: Albumin, calcium, cholesterol, selenium, triglyceride, urea. uric acid