The refi nement of unsaturated fatty acids (UFA) from Hippophae rhamnoides L. seed oil was carried out by molecular distillation (MD) using response surface methodology (RSM). A central composite rotate design was used in order to optimize the experimental parameters: distilling temperature and feed fl ow. The optimal MD conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The results suggested that the distilling temperature and feed fl ow signifi cantly affected both the UFA content and oil yield in the two models. The optimum conditions for refi ning UFA were: distilling temperature 107.5 °C and feed fl ow 1 ml min -1 . Optimal values predicted by RSM for the UFA content and oil yield were 82.38% and 62.59%, respectively. Close agreement between experimental and predicted values was obtained.