Recent improvements in the field of flow-through-electrophoresis are presented. These improvements make it possible to run flow through electrophoresis with the same precision, but more economically and more easily than the formerly described apparatus. This was achieved by limiting the original system to slab gels only. This leads to a considerable reduction in the size of the apparatus and to simplification of its handling. Although the gel width is reduced to 10 mm, the apparatus is suitable for the analysis of mg as well as g quantities.The usefulness of this method is demonstrated by the analysis of samples obtained during the isolation and purification of collagen type II, and by the analysis of insulin samples and other substances. The procedure is also suitable for SDS-electrophoresis under flow-through conditions, enabling a simple and fast separation of proteins and determination of their molecular masses.