In our "plastic" world the role of the herbs and the medical products is rising. One of the important herbs is sea buckthorn. The main goal of our work was to examine the possibility of using membrane separation to concentrate sea buckthorn juice and to give the basis of further products (e.g. instant tea) with it. During our experiments the concentration of the juice was examined with the combination of microfiltration (MF) and reverse osmosis (RO1), with nanofiltration (NF) and with reverse osmosis (RO2) without clarification. The operating parameters were determined during the measurements, and the concentrations were carried out on them. The analytical assay of the juice such as the determination of the solid content, Vitamin C content, antioxidant activity, was also done. The modelling of the process was based on the mathematical model which was worked out previously for instant coffee. The modelling was done only for reverse osmosis. (C) 2006 Elsevier B.V. All rights reserved.