Paired cell alignment of mouse myeloma by dielectrophoretic phenomena was carried out using a jagged microarray electrode. A.c. voltage application (0.1-1 V rms, 0.1-10 MHz) forced the cells to move into projection gaps where non-uniform, locally-intense electric fields were created. A highly selective one-to-one cell alignment (ca. 50%) was observed at the array electrode with 10 μm projection gaps. Since the dielectrophoretic force acted effectively on living cells, the present array electrode selected living cells to form one-to-one cell alignment from the suspension mixture of living and dead cells.