Abstract: The aim of this study is the evaluation of the effect of one group of surfactants including polyethylene glycol sorbitan esters (Tweens: 20, 40, 60 and 80) on Red Blood Cells (RBC) as a model for biological membranes. Also in this study some of physicochemical properties including Emulsification index (E24) and Foam producing activity (Fh) were studied. In this study the hemolytic effect of four surfactants from Tween category were evaluated. Surfactants solutions were prepared in McIvan`s buffer in specific concentration. 0.2 mL of RBC was mixed with 0.2 mL of one of surfactants solution incubated in four different temperatures for two different times. The absorbance of the samples was determined by UV spectrophotometer. Each test was done nine times. The results were shown by mean±SD. E24 and Fh were also determined for each surfactant solutions. In comparison of the four studied surfactants, Tween 20 have the highest hemolytic effect and the Tween 80 is the lowest one. The values of E24 and Fh have good correlation with Hydrophilic-Lipophilic Balance (HLB) values. Increasing in HLB value lead to increasing in those parameters.