With a small amount of an electrolyte, electroforrnation of giant vesicles (GVs) proceeded faster than in pure water. In 50 mu M neutral phosphate buffer, a GV larger than 50 mu m formed in 100 s. The time required for the completion was 5-10 min while electroformation in pure water usually takes 90-120 min. The rapid formation was observed with various electrolytes but only of appropriate concentration (for phosphate buffer, 40-200 mu M) and not with a nonelectrolyte such as glucose.