Abstract: The invention provides a method and apparatus for the delivery of polynucleotide cancer vaccines to increase T cell response and reduce pain due to long electric waveform application and muscle contractions. The method includes the steps of: (a.) administering a polynucleotide cancer vaccine into the skin at an administration site, (b.) applying a needle electrode to the skin in the vicinity of the administration site, and (c.) applying a sequence of at least three electrical waveforms to deliver the polynucleotide cancer vaccine into skin cells by electroporation. The sequence has at least one of the following characteristics {1} at least two of the waveforms differ in amplitude, {2} at least two of the waveforms differ in width, and (3) a first waveform interval for a first set of two of the waveforms is different from a second waveform interval for a second set of two of the waveforms.