A simple procedure for the preparation of agarose suitable for electrophoresis is developed in which anionic polysaccharides are removed by extracting the agar gel-granules with phosphate buffer (0.03 M, pH 6.8) containing urea (4 M), followed by electrophoresis in the same buffer system. Further, alkali treatment in the presence of sodium borohydride, eliminates electroendosmosis, giving essentially a neutral agarose, as judged by the electrophoretic behaviour of basic substances like crystal violet and cytochrome C. The purified agarose with yields 60-65%, has a sulphur content less than 0.1%, and forms rigid, transparent gels.