An apparatus for implanting macromolecules such as genes, DNA or pharmaceuticals into a preselected surface tissue region of of a patient. An applicator having a plurality of electrodes is provided for contacting a surface tissue region of a patient. A mechanism associated with the applicator delivers a predetermined quantity of a fluid medium carrying the preselected macromolecules. A signal generator is provided for generating a predetermined electric signal. The electrodes of the applicator are connected to the signal generator for applying an electric field in the surface tissue region. The field has a predetermined strength and duration in order to make the walls of a plurality of cells in the surface tissue region transiently permeable to permit the macromolecules to enter said preselected cells without damaging said cells. This enhances the uptake of macromolecules and thus enhances the therapeutic effect achieved.