Selenium is an essential trace element that is important in proper immune system functioning and in free radical control. Selenium protects against heart weakness and degeneration. It is crucial for optimal health and detoxification. Selenium is required for the production of thyroid hormones. The body only needs a small amount. Nevertheless, the selenium mineral is an essential mineral which the body requires on a daily basis. The objective of the work concerns the proposal and development of the technique for the measurement of selenium levels in the human blood samples by a simple spectrophotometeric determination in diseased and health conditions.