Abstract: The present invention is directed to methods and apparatus for simultaneous gel electrophoresis analysis of multiple nucleic acid samples. The invention provides an electrophoresis gel-matrix layer having two mutually opposite ends for application of an electrophoresis voltage thereto, an exposed major surface extending between the two ends, and a plurality of wells in the thickness of the layer and open at said exposed surface, wherein the wells are arranged in a plurality of rows each extending transversely of the end-to-end direction of the layer and wherein the wells in successive rows are aligned with each other so as to form columns which are aligned in the end-to-end direction said gel-matrix layer further comprising two slots positioned at opposing ends of the plurality of open sample wells for insertion of electrophoresis electrodes.