A continuous flow electro-manipulator available both for mass production of fused and of transfected plant protoplasts was devised using a flow chamber with gold-coated glass panel electrodes. Up to 100 ml of protoplasts suspension were treated within 20 min at the rate of approximately 1×10(6) protoplasts / min. The yield of diheterokaryons between tobacco mesophyll and carrot root protoplasts reached approximately 10 % of total protoplasts by flow electro-fusion. More than 95 % of tobacco and cowpea mesophyll protoplasts became infected with tobacco mosaic virus RNA by flow electro-transfection.