The aim of the present work is to study the effect of He-Ne laser (632.8 nm, 2 mm spot diameter, 30 mW, and continuous pulse) on the properties of human blood during different storage periods and seeking for the optimum laser dose to enhance blood shelf life. Human blood from five healthy donors was collected in human blood bags under the supervision of the center blood bank. The control and treated samples were stored in center blood bank refrigerator at 2-60C. The collected blood was divided into 4 groups, one for the control sample and the three other groups for the irradiation with different doses of He-Ne laser (0.0287, 0.0563 and 0.198 J/cm2 ). Each group was sub-divided into 6 samples to perform during storage days (9, 24, 30, 35, 42, & 50). The measurements of the fragility (Ϝ) and viscosity (η) values of all samples during the storage days suggested that the He-Ne laser at a dose 0.198 J/cm2 is working to increase the resistance of the membrane of the red blood cells (RBC) and consequently the storage period increases form 35 day to 42 days. In addition, viscosity for human blood before and after exposure to He-Ne laser dose of 0.198 J/cm2 reflects the validity of the blood during the storage period. The obtained data proved that the ability of using the recommended He-Ne laser dose 0.198 J/cm2 to improve the rheological properties and prolong the storage period of human blood from 35 days to 42 days.