Abstract: The influence of dextran and its anion derivates (blue dextran, cibacron blue dexran, fluoresceinythiocarbamoyl dextran) on the electrofusion of barley protoplasts has been investigated. It was found that as a kind of neutral surface active agent, dextran could promote the electrofusion, but these anion derivates could decrease the electrofusion yield. The phenomena were discussed from the view of adsorption of additives on the cell membrane.