Ionic substances were injected electrophoretically into a single bio-cell of plants with an MME. K+ and Cl- ions were injected into a water drop with 100 mu m diameter and a plant leaf cell of spiderwort, and their concentrations were measured with respective ion-sensitive microelectrodes. An anionic fluorescent dye, LY, was injected in the same way and its concentration was estimated by a microscopic image analyzing system. Liposomes containing a fluorescent dye (LY or DAPI) were prepared and injected into a single cell of cultured tobacco, line BY-2. In the particular case of DAPI-liposomes, the cells were not fluorescent initially but they turned fluorescent after the exposure of pulsing electric field. That was speculated as the leakage of DAPI from the liposomes and the generation of fluorescent conjugates of DAPI and DNA. These results show that an MME is a useful device for the control of the quantity and the timing of microinjection into a single bio-cell and therefore a powerful tool in the molecular analysis of cell-to-cell communication.