Electroporation is an efficient method of introducing foreign impermeant molecules such as drugs and genes into cells. Conventional electroporation has been based on the application of short electrical pulses (electropulsation). Electropulsation requires specialized equipment and cannot be integrated easily with techniques such as electrophoresis which is based on constant voltage. Here we demonstrate the delivery of small molecules and genes into cells, using a microfluidic electroporation technique based on constant direct current (DC) voltage that we developed earlier. We demonstrate the delivery of two molecules into Chinese hamster ovary (CHO-K1) cells: a membrane impermeable nucleic acid dye (SYTOX Green) and a plasmid vector carrying the gene for green fluorescent protein (pEGFP-C1). Our devices can exert field variations to flowing cells that are analogous to the application of single or multiple pulses by having different geometries. We investigate the effects of the electrical parameters and different geometries of the device on the transfection efficiency and cell viability. Our technique provides a simple solution to electroporation-based drug and gene delivery by eliminating the need for a pulse generator. We envision that these simple microscale electroporation devices will have the potential to work in parallel on a microchip platform and such technology will allow high-throughput functional screening of drugs and genes.