We present the results of a study on the influence of albumin and prolactin concentrations and intravascular fluid pH on vein permeability for albumin. Permeability conditions were simulated depending on albumin concentration, pH value and prolactin concentration. In research model an in vitro method was applied using natural membrane - porcine vena cava inferior. Vein permeability was in the 0.63% to 5.69% range. In control variant permeability was ~2.54% and increased ~2 fold at decreased albumin and PRL concentrations. At increased albumin concentration permeability was decreased 4-fold. Albumin concentration significantly influences albumin permeability.